SEC Filing | Tenaris

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UNITED STATES SECURITIES AND EXHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 36)* TUBOS DE ACERO DE MEXICO, S.A. (Name of Issuer) Common Stock (Title of Class of Securities) 898592506 (CUSIP Number) Mr. Fernando R. Mantilla Av. Leandro N. Alem 1067, 28th Floor, 1001 - Buenos Aires, Argentina (54-11) 4018-2245 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) March 31, 2003 (Date of Event which Requires Filing of this Statement) If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of ss.ss.240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. |_| Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See ss.240.13d-7 for other parties to whom copies are to be sent. *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page. The information required on the remainder of this cover page shall not bee deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 898592506 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). ROBERTO ROCCA - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (See Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. Source of Funds (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) - -------------------------------------------------------------------------------- 6. Citizenship or Place of Organization ITALY - -------------------------------------------------------------------------------- Number of 7. Sole Voting Power NONE Shares Bene- ------------------------------------------------------------ ficially Owned by Each Reporting 8. Shared Voting Power: 324,064,223 Shares of TAMSA Person With Common Stock (1 ADR=5 shares) ------------------------------------------------------------ 9. Sole Dispositive Power NONE ------------------------------------------------------------ 10. Shared Dispositive Power 324,064,223 Shares of TAMSA Common Stock (1 ADR=5 shares) - -------------------------------------------------------------------------------- 11. Aggregate Amount Beneficially Owned by Each Reporting Person 324,064,223 - -------------------------------------------------------------------------------- 12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 13. Percent of Class Represented by Amount in Row (11) 94.50% - -------------------------------------------------------------------------------- 14. Type of Reporting Person (See Instructions) IN ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------

CUSIP No. 898592506 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). SIDERCA Sociedad Anonima Industrial y Comercial - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (See Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. Source of Funds (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) - -------------------------------------------------------------------------------- 6. Citizenship or Place of Organization ARGENTINA - -------------------------------------------------------------------------------- Number of 7. Sole Voting Power NONE Shares Bene- ------------------------------------------------------------ ficially Owned by Each Reporting 8. Shared Voting Power: 324,064,223 Shares of TAMSA Person With Common Stock (1 ADR=5 shares) ------------------------------------------------------------ 9. Sole Dispositive Power NONE ------------------------------------------------------------ 10. Shared Dispositive Power 324,064,223 Shares of TAMSA Common Stock (1 ADR=5 shares) - -------------------------------------------------------------------------------- 11. Aggregate Amount Beneficially Owned by Each Reporting Person 324,064,223 - -------------------------------------------------------------------------------- 12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 13. Percent of Class Represented by Amount in Row (11) 94.50% - -------------------------------------------------------------------------------- 14. Type of Reporting Person (See Instructions) CO ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------

CUSIP No. 898592506 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). SIDERCA INTERNATIONAL ApS - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (See Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. Source of Funds (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) - -------------------------------------------------------------------------------- 6. Citizenship or Place of Organization DENMARK - -------------------------------------------------------------------------------- Number of 7. Sole Voting Power NONE Shares Bene- ------------------------------------------------------------ ficially Owned by Each Reporting 8. Shared Voting Power: 324,064,223 Shares of TAMSA Person With Common Stock (1 ADR=5 shares) ------------------------------------------------------------ 9. Sole Dispositive Power NONE ------------------------------------------------------------ 10. Shared Dispositive Power 324,064,223 Shares of TAMSA Common Stock (1 ADR=5 shares) - -------------------------------------------------------------------------------- 11. Aggregate Amount Beneficially Owned by Each Reporting Person 324,064,223 - -------------------------------------------------------------------------------- 12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 13. Percent of Class Represented by Amount in Row (11) 94.50% - -------------------------------------------------------------------------------- 14. Type of Reporting Person (See Instructions) CO ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------

CUSIP No. 898592506 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). ROCCA & PARTNERS Sociedad Anonima - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (See Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. Source of Funds (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) - -------------------------------------------------------------------------------- 6. Citizenship or Place of Organization BRITISH VIRGIN ISLANDS - -------------------------------------------------------------------------------- Number of 7. Sole Voting Power NONE Shares Bene- ------------------------------------------------------------ ficially Owned by Each Reporting 8. Shared Voting Power: 324,064,223 Shares of TAMSA Person With Common Stock (1 ADR=5 shares) ------------------------------------------------------------ 9. Sole Dispositive Power NONE ------------------------------------------------------------ 10. Shared Dispositive Power 324,064,223 Shares of TAMSA Common Stock (1 ADR=5 shares) - -------------------------------------------------------------------------------- 11. Aggregate Amount Beneficially Owned by Each Reporting Person 324,064,223 - -------------------------------------------------------------------------------- 12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 13. Percent of Class Represented by Amount in Row (11) 94.50% - -------------------------------------------------------------------------------- 14. Type of Reporting Person (See Instructions) CO ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------

CUSIP No. 898592506 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). SAN FAUSTIN N.V. - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (See Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. Source of Funds (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) - -------------------------------------------------------------------------------- 6. Citizenship or Place of Organization NETHERLANDS ANTILLES - -------------------------------------------------------------------------------- Number of 7. Sole Voting Power NONE Shares Bene- ------------------------------------------------------------ ficially Owned by Each Reporting 8. Shared Voting Power: 324,064,223 Shares of TAMSA Person With Common Stock (1 ADR=5 shares) ------------------------------------------------------------ 9. Sole Dispositive Power NONE ------------------------------------------------------------ 10. Shared Dispositive Power 324,064,223 Shares of TAMSA Common Stock (1 ADR=5 shares) - -------------------------------------------------------------------------------- 11. Aggregate Amount Beneficially Owned by Each Reporting Person 324,064,223 - -------------------------------------------------------------------------------- 12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 13. Percent of Class Represented by Amount in Row (11) 94.50% - -------------------------------------------------------------------------------- 14. Type of Reporting Person (See Instructions) CO ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------

CUSIP No. 898592506 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). SIDERTUBES S.A. - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (See Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. Source of Funds (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) - -------------------------------------------------------------------------------- 6. Citizenship or Place of Organization LUXEMBOURG - -------------------------------------------------------------------------------- Number of 7. Sole Voting Power NONE Shares Bene- ------------------------------------------------------------ ficially Owned by Each Reporting 8. Shared Voting Power: 324,064,223 Shares of TAMSA Person With Common Stock (1 ADR=5 shares) ------------------------------------------------------------ 9. Sole Dispositive Power NONE ------------------------------------------------------------ 10. Shared Dispositive Power 324,064,223 Shares of TAMSA Common Stock (1 ADR=5 shares) - -------------------------------------------------------------------------------- 11. Aggregate Amount Beneficially Owned by Each Reporting Person 324,064,223 - -------------------------------------------------------------------------------- 12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 13. Percent of Class Represented by Amount in Row (11) 94.50% - -------------------------------------------------------------------------------- 14. Type of Reporting Person (See Instructions) CO ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------

CUSIP No. 898592506 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). I.I.I. INDUSTRIAL INVESTMENTS INC. - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (See Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. Source of Funds (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) - -------------------------------------------------------------------------------- 6. Citizenship or Place of Organization BRITISH VIRGIN ISLANDS - -------------------------------------------------------------------------------- Number of 7. Sole Voting Power NONE Shares Bene- ------------------------------------------------------------ ficially Owned by Each Reporting 8. Shared Voting Power: 324,064,223 Shares of TAMSA Person With Common Stock (1 ADR=5 shares) ------------------------------------------------------------ 9. Sole Dispositive Power NONE ------------------------------------------------------------ 10. Shared Dispositive Power 324,064,223 Shares of TAMSA Common Stock (1 ADR=5 shares) - -------------------------------------------------------------------------------- 11. Aggregate Amount Beneficially Owned by Each Reporting Person 324,064,223 - -------------------------------------------------------------------------------- 12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 13. Percent of Class Represented by Amount in Row (11) 94.50% - -------------------------------------------------------------------------------- 14. Type of Reporting Person (See Instructions) CO ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------

CUSIP No. 898592506 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). TENARIS S.A. - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (See Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. Source of Funds (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) - -------------------------------------------------------------------------------- 6. Citizenship or Place of Organization LUXEMBOURG - -------------------------------------------------------------------------------- Number of 7. Sole Voting Power NONE Shares Bene- ------------------------------------------------------------ ficially Owned by Each Reporting 8. Shared Voting Power: 324,064,223 Shares of TAMSA Person With Common Stock (1 ADR=5 shares) ------------------------------------------------------------ 9. Sole Dispositive Power NONE ------------------------------------------------------------ 10. Shared Dispositive Power 324,064,223 Shares of TAMSA Common Stock (1 ADR=5 shares) - -------------------------------------------------------------------------------- 11. Aggregate Amount Beneficially Owned by Each Reporting Person 324,064,223 - -------------------------------------------------------------------------------- 12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 13. Percent of Class Represented by Amount in Row (11) 94.50% - -------------------------------------------------------------------------------- 14. Type of Reporting Person (See Instructions) CO ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------

CUSIP No. 898592506 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). INVERTUB S.A. - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (See Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. Source of Funds (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) - -------------------------------------------------------------------------------- 6. Citizenship or Place of Organization ARGENTINA - -------------------------------------------------------------------------------- Number of 7. Sole Voting Power NONE Shares Bene- ------------------------------------------------------------ ficially Owned by Each Reporting 8. Shared Voting Power: 324,064,223 Shares of TAMSA Person With Common Stock (1 ADR=5 shares) ------------------------------------------------------------ 9. Sole Dispositive Power NONE ------------------------------------------------------------ 10. Shared Dispositive Power 324,064,223 Shares of TAMSA Common Stock (1 ADR=5 shares) - -------------------------------------------------------------------------------- 11. Aggregate Amount Beneficially Owned by Each Reporting Person 324,064,223 - -------------------------------------------------------------------------------- 12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 13. Percent of Class Represented by Amount in Row (11) 94.50% - -------------------------------------------------------------------------------- 14. Type of Reporting Person (See Instructions) CO ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------

CUSIP No. 898592506 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). SIDTAM LIMITED - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (See Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. Source of Funds (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) - -------------------------------------------------------------------------------- 6. Citizenship or Place of Organization BRITISH VIRGIN ISLANDS - -------------------------------------------------------------------------------- Number of 7. Sole Voting Power NONE Shares Bene- ------------------------------------------------------------ ficially Owned by Each Reporting 8. Shared Voting Power: 324,064,223 Shares of TAMSA Person With Common Stock (1 ADR=5 shares) ------------------------------------------------------------ 9. Sole Dispositive Power NONE ------------------------------------------------------------ 10. Shared Dispositive Power 324,064,223 Shares of TAMSA Common Stock (1 ADR=5 shares) - -------------------------------------------------------------------------------- 11. Aggregate Amount Beneficially Owned by Each Reporting Person 324,064,223 - -------------------------------------------------------------------------------- 12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) NOT APPLICABLE - -------------------------------------------------------------------------------- 13. Percent of Class Represented by Amount in Row (11) 94.50% - -------------------------------------------------------------------------------- 14. Type of Reporting Person (See Instructions) CO ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------ ------------------------------------------------------------

AMENDMENT No. 36 TO SCHEDULE 13D This Amendment No. 36 amends the Statement on Schedule 13D originally filed on September 24, 1992 and amended and restated as of November 11, 2002, as amended ("Schedule 13D"), on behalf of Roberto Rocca, Siderca Sociedad Anonima, Industrial y Comercial ("Siderca SAIC"), and Siderca International ApS ("Siderca ApS"), together with Rocca & Partners S.A. ("Rocca & Partners"), San Faustin N.V. ("San Faustin"), Sidertubes S.A. ("Sidertubes"), I.I.I. Industrial Investments Inc. ("III BVI"), Tenaris S.A. ("Tenaris"), Invertub Sociedad Anonima ("Invertub") and Sidtam Limited ("Sidtam") (collectively, "Reporting Persons"), relating to the common shares, without par value (the "TAMSA Shares"), of Tubos de Acero de Mexico, S.A., a Mexican company ("TAMSA"). Item 2. Identity and Background No changes except the following: On January 31, 2003, the board of directors of Tenaris approved the appointment of Tenaris's principal corporate officers effective immediately. Reference is made to the press release issued by Tenaris on January 31, 2003, announcing the appointment of these corporate officers. An updated list of the directors and executive officers of Tenaris and the information required by subparagraphs (a) through (c) and subparagraph (f) of Item 2 of Schedule 13D, as such information pertains to the directors and executive officers of Tenaris, is set forth on Schedule A and is hereby incorporated herein by reference. To the best knowledge of the Reporting Persons, none of the executive officers of Tenaris has during the last five years been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws. Item 4. Purpose of the Transaction Reference is made to the press release issued by Tenaris on March 31, 2003, announcing that, subject to the approvals of the U.S. and Mexican securities regulators and TAMSA's extraordinary shareholders meeting, Tenaris intends to effect an exchange of its shares and ADSs for any TAMSA shares and ADSs not held by Tenaris or its affiliates in accordance with Mexican and U.S. laws. Tenaris also reported in its March 31, 2003 press release that it currently does not expect to obtain the requisite approvals, and consequently be in a position to effect any exchange of shares and ADSs, prior to June 2003.

Item 5. Interest in Securities of the Issuer No changes. Item 7. Material to be Filed as Exhibits The press release of Tenaris, dated January 31, 2003, announcing the appointment of its audit committee and principal corporate officers, is filed as an exhibit hereto. The press release of Tenaris, dated March 31, 2003, announcing Tenaris's intent to effect an exchange of its shares and ADSs for any TAMSA shares and ADSs not held by Tenaris or its affiliates, is filed as an exhibit hereto. Powers of attorney for Tenaris S.A., I.I.I. Industrial Investments Inc. and Invertub S.A. are incorporated by reference into this Amendment to the ones filed as exhibits to Amendment No. 34 to the Schedule 13D. Powers of attorney for each of the other Reporting Persons are incorporated by reference into this Amendment to the ones filed as exhibits to Amendment No. 23 to the Schedule 13D of Siderca ApS. The written agreement of the Reporting Persons related to the filing of this Schedule 13D as required by Rule 13d-k(1)(iii) is included in the signature pages hereto and is hereby filed as an exhibit hereto.

Schedule A Tenaris S.A. - ------------------------------------------------------------------------------------------------------------------- Executive Officers Business Address Present Principal Citizenship Occupation - ------------------------------------------------------------------------------------------------------------------- Roberto Rocca - Chairman Av. Leandro N. Alem 1067, Honorary Chairman of San Italian of the Board of Directors Buenos Aires - Argentina Faustin N.V., President of Dalmine and President of Siderca - ------------------------------------------------------------------------------------------------------------------- Paolo Rocca - President and Av. Leandro N. Alem 1067, President and Chief Italian Chief Executive Officer Buenos Aires - Argentina Executive Officer of Tenaris - ------------------------------------------------------------------------------------------------------------------- Carlos Condorelli -Chief Av. Leandro N. Alem 1067, Chief Financial Officer Argentine Financial Officer Buenos Aires - Argentina of Tenaris - ------------------------------------------------------------------------------------------------------------------- Cecilia Bilesio - Corporate Edificio Parque Reforma, Corporate Secretary of Argentine Secretary Campos Eliseos 400, 11560 Tenaris Mexico, D.F., Mexico - ------------------------------------------------------------------------------------------------------------------- Directors Business Address Present Principal Citizenship Occupation - ------------------------------------------------------------------------------------------------------------------- Roberto Bonatti Av. Leandro N. Alem 1067, President of San Faustin Italian Buenos Aires - Argentina N.V. - ------------------------------------------------------------------------------------------------------------------- Carlos Franck Av. Leandro N. Alem 1067, President of Santa Maria Argentine Buenos Aires - Argentina S.A.I.F. - ------------------------------------------------------------------------------------------------------------------- Pedro Pablo Kuczynski 2665 South Bay Shore President and Chief Peruvian Drive, Suite 1101 Executive Officer, Latin Coconut Grove America Enterprise Fund, Miami, Florida 33133 USA USA - ------------------------------------------------------------------------------------------------------------------- Bruno Marchettini Av. Leandro N. Alem 1067, Director of Siderar S.A., Italian Buenos Aires - Argentina and director of Siderca - ------------------------------------------------------------------------------------------------------------------- Gianfelice Mario Rocca Av. Leandro N. Alem 1067, Chairman of San Faustin Italian Buenos Aires - Argentina N.V. - ------------------------------------------------------------------------------------------------------------------- Paolo Rocca Av. Leandro N. Alem 1067, President and Chief Italian Buenos Aires - Argentina Executive Officer of Tenaris - -------------------------------------------------------------------------------------------------------------------

- ------------------------------------------------------------------------------------------------------------------- Roberto Rocca Av. Leandro N. Alem 1067, Honorary Chairman of San Italian Chairman of the Board of Buenos Aires - Argentina Faustin N.V., President Directors of Dalmine and President of Siderca - ------------------------------------------------------------------------------------------------------------------- Jaime Serra Puche Prol. Paseo de la Reforma A partner in S.A.I. Mexican 600, Desp. 103 Consultores S.C., Mexico 01210-Mexico D.F. - ------------------------------------------------------------------------------------------------------------------- Amadeo Vazquez y Vazquez Austria 2670-3(0)piso, President of Telecom Argentine (1425) Buenos Aires - Argentina, a director of Argentina Siderca, a director of BBVA Banco Frances S.A., a member of the board of the Buenos Aires Stock Exchange, Vice President of the Fundacion Mediterranea and Vice-President Finance of Tenaris - ------------------------------------------------------------------------------------------------------------------- Guillermo F. Vogel Edificio Parque Reforma, Vice Chairman of Tamsa Mexican Campos Eliseos 400, 11560 and Vice-President Mexico, D.F., Mexico Finance of Tenaris - -------------------------------------------------------------------------------------------------------------------

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I, Fernando Mantilla, attorney duly authorized by ROBERTO ROCCA to sign this statement, certify that the information set forth in this Schedule 13D is true, complete and correct. Pursuant to Rule 13d-1(k)(1), the undersigned joins in the filing of this Schedule 13D on his own behalf and on behalf of ROCCA & PARTNERS S.A., SAN FAUSTIN N.V., SIDERCA Sociedad Anonima Industrial y Comercial, SIDERCA INTERNATIONAL ApS, SIDERTUBES S.A., I.I.I. INDUSTRIAL INVESTMENTS Inc., TENARIS S.A., INVERTUB Sociedad Anonima and SIDTAM LIMITED. April 2, 2003 /s/ Fernando Mantilla ------------------------------- Fernando Mantilla Attorney-in-fact

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I, Fernando Mantilla, attorney duly authorized by ROCCA & PARTNERS S.A. to sign this statement, certify that the information set forth in this Schedule 13D is true, complete and correct. Pursuant to Rule 13d-1(k)(1), the undersigned joins in the filing of this Schedule 13D on his own behalf and on behalf of Roberto ROCCA, SAN FAUSTIN N.V., SIDERCA Sociedad Anonima Industrial y Comercial, SIDERCA INTERNATIONAL ApS, SIDERTUBES S.A., I.I.I. INDUSTRIAL INVESTMENTS Inc., TENARIS S.A., INVERTUB Sociedad Anonima and SIDTAM LIMITED. April 2, 2003 /s/ Fernando Mantilla ------------------------------- Fernando Mantilla Attorney-in-fact

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I, Fernando Mantilla, attorney duly authorized by SAN FAUSTIN N.V. to sign this statement, certify that the information set forth in this Schedule 13D is true, complete and correct. Pursuant to Rule 13d-1(k)(1), the undersigned joins in the filing of this Schedule 13D on his own behalf and on behalf of Roberto ROCCA, ROCCA & PARTNERS S.A., SIDERCA Sociedad Anonima Industrial y Comercial, SIDERCA INTERNATIONAL ApS, SIDERTUBES S.A., I.I.I. INDUSTRIAL INVESTMENTS Inc., TENARIS S.A., INVERTUB Sociedad Anonima and SIDTAM LIMITED. April 2, 2003 /s/ Fernando Mantilla ------------------------------- Fernando Mantilla Attorney-in-fact

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I, Fernando Mantilla, attorney duly authorized by I.I.I. INDUSTRIAL INVESTMENTS Inc. to sign this statement, certify that the information set forth in this Schedule 13D is true, complete and correct. Pursuant to Rule 13d-1(k)(1), the undersigned joins in the filing of this Schedule 13D on his own behalf and on behalf of Roberto ROCCA, ROCCA & PARTNERS S.A., SAN FAUSTIN N.V., SIDERCA Sociedad Anonima Industrial y Comercial, SIDERCA INTERNATIONAL ApS, SIDERTUBES S.A., TENARIS S.A., INVERTUB Sociedad Anonima and SIDTAM LIMITED. April 2, 2003 /s/ Fernando Mantilla ------------------------------- Fernando Mantilla Attorney-in-fact

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I, Fernando Mantilla, attorney duly authorized by SIDERTUBES S.A. to sign this statement, certify that the information set forth in this Schedule 13D is true, complete and correct. Pursuant to Rule 13d-1(k)(1), the undersigned joins in the filing of this Schedule 13D on his own behalf and on behalf of Roberto ROCCA, ROCCA & PARTNERS S.A., SAN FAUSTIN N.V., SIDERCA Sociedad Anonima Industrial y Comercial, SIDERCA INTERNATIONAL ApS, I.I.I. INDUSTRIAL INVESTMENTS Inc., INVERTUB Sociedad Anonima, TENARIS S.A. and SIDTAM LIMITED. April 2, 2003 /s/ Fernando Mantilla ------------------------------- Fernando Mantilla Attorney-in-fact

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I, Fernando Mantilla, attorney duly authorized by TENARIS S.A. to sign this statement, certify that the information set forth in this Schedule 13D is true, complete and correct. Pursuant to Rule 13d-1(k)(1), the undersigned joins in the filing of this Schedule 13D on his own behalf and on behalf of Roberto ROCCA, ROCCA & PARTNERS S.A., SAN FAUSTIN N.V., SIDERCA Sociedad Anonima Industrial y Comercial, SIDERCA INTERNATIONAL ApS, SIDERTUBES S.A., I.I.I. INDUSTRIAL INVESTMENTS Inc., INVERTUB Sociedad Anonima and SIDTAM LIMITED. April 2, 2003 /s/ Fernando Mantilla ------------------------------- Fernando Mantilla Attorney-in-fact

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I, Fernando Mantilla, attorney duly authorized by INVERTUB S.A. to sign this statement, certify that the information set forth in this Schedule 13D is true, complete and correct. Pursuant to Rule 13d-1(k)(1), the undersigned joins in the filing of this Schedule 13D on his own behalf and on behalf of Roberto ROCCA, ROCCA & PARTNERS S.A., SAN FAUSTIN N.V., SIDERCA Sociedad Anonima Industrial y Comercial, SIDERCA INTERNATIONAL ApS, SIDERTUBES S.A., I.I.I. INDUSTRIAL INVESTMENTS Inc., TENARIS S.A. and SIDTAM LIMITED. April 2, 2003 /s/ Fernando Mantilla ------------------------------- Fernando Mantilla Attorney-in-fact

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I, Fernando Mantilla, attorney duly authorized by SIDERCA SOCIEDAD ANONIMA INDUSTRIAL Y COMERCIAL to sign this statement, certify that the information set forth in this Schedule 13D is true, complete and correct. Pursuant to Rule 13d-1(k)(1), the undersigned joins in the filing of this Schedule 13D on his own behalf and on behalf of Roberto ROCCA, ROCCA & PARTNERS S.A., SAN FAUSTIN N.V., SIDERCA INTERNATIONAL ApS, SIDERTUBES S.A., I.I.I. INDUSTRIAL INVESTMENTS Inc., TENARIS S.A., INVERTUB S.A. and SIDTAM LIMITED. April 2, 2003 /s/ Fernando Mantilla ------------------------------- Fernando Mantilla Attorney-in-fact

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I, Fernando Mantilla, attorney duly authorized by SIDERCA INTERNATIONAL ApS to sign this statement, certify that the information set forth in this Schedule 13D is true, complete and correct. Pursuant to Rule 13d-1(k)(1), the undersigned joins in the filing of this Schedule 13D on his own behalf and on behalf of Roberto ROCCA, ROCCA & PARTNERS S.A., SAN FAUSTIN N.V., SIDERCA Sociedad Anonima Industrial y Comercial, SIDERTUBES S.A., I.I.I. INDUSTRIAL INVESTMENTS Inc., TENARIS S.A., INVERTUB Sociedad Anonima and SIDTAM LIMITED. April 2, 2003 /s/ Fernando Mantilla ------------------------------- Fernando Mantilla Attorney-in-fact

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I, Fernando Mantilla, attorney duly authorized by SIDTAM LIMITED to sign this statement, certify that the information set forth in this Schedule 13D is true, complete and correct. Pursuant to Rule 13d-1(k)(1), the undersigned joins in the filing of this Schedule 13D on his own behalf and on behalf of Roberto ROCCA, ROCCA & PARTNERS S.A., SAN FAUSTIN N.V., SIDERCA Sociedad Anonima Industrial y Comercial, SIDERCA INTERNATIONAL ApS, I.I.I. INDUSTRIAL INVESTMENTS Inc., TENARIS S.A. INVERTUB Sociedad Anonima and SIDERTUBES S.A. April 2, 2003 /s/ Fernando Mantilla ------------------------------- Fernando Mantilla Attorney-in-fact

Exhibit index: 99.1 Press release of Tenaris, dated January 31, 2003, announcing the appointment of its audit committee and principal corporate officers 99.2 Press release of Tenaris, dated March 31, 2003, announcing Tenaris's intent to effect an exchange of its shares and ADSs for any TAMSA shares and ADSs not held by Tenaris or its affiliates 99.3 Powers of attorney (incorporated by reference to Amendments No. 23 and 34) 99.4 Written agreement of the Reporting Persons (included in signature pages)

                                                                    Exhibit 99.1

[LOGO] Tenaris Press Release

Tenaris Appoints Audit Committee and Principal Corporate Officers

Luxembourg,  January 31, 2003 - Tenaris S.A. (TS: NYSE, Buenos Aires, Mexico and
TEN: Italy),  in the first meeting of its board of directors as a public company
held in Milan on January 31, 2003,  approved the  appointment  of the  following
authorities and corporate officers with immediate effect:

       Roberto Rocca as Chairman of the board of directors

       Paolo Rocca as President and Chief Executive Officer

       Carlos Condorelli as Chief Financial Officer, and

       Cecilia Bilesio as Corporate Secretary.

The board of  directors  also  appointed,  from among its  members,  Jaime Serra
Puche,  Amadeo Vazquez y Vazquez and Guillermo  Vogel to be members of the Audit
Committee in accordance with the Articles of Association.

Tenaris, a multinational organized in Luxembourg,  is a leading manufacturer and
supplier  of steel pipe  products  and  associated  services to the oil and gas,
energy and mechanical industries.

More information about Tenaris is available at  www.tenaris.com.  Information on
or accessible through this website is not part of this press release.

                                                                    Exhibit 99.2

[LOGO] Tenaris Press Release

Gerardo Varela
Tenaris
1-888 300 5432
www.tenaris.com

Tenaris Announces Plan for the Acquisition of Remaining Minority Interests in
Tamsa

LUXEMBOURG (March 31, 2003). Tenaris S.A. (NYSE, BASE and Mexico: TS; MTA Italy:
TEN), announced today that it plans to acquire any remaining minority interests
in Tubos de Acero de Mexico S.A. - Tamsa (AMEX: TAM and Mexico: TAMSA). In
addition, Tenaris announced that it intends to cause the delisting of Tamsa from
the Mexican Stock Exchange and the American Stock Exchange, the termination of
Tamsa's ADR facility and, if and when appropriate, the termination of Tamsa's
registration with the U.S. Securities and Exchange Commission (the SEC). Tenaris
currently holds, directly or indirectly, 94.5% of the shares and ADSs of Tamsa.

Subject to the approvals of the U.S. and Mexican securities regulators and
Tamsa's extraordinary shareholders meeting, Tenaris intends to effect an
exchange of its shares and ADSs for any Tamsa shares and ADSs not held by
Tenaris or its affiliates in accordance with Mexican and U.S. laws. Tenaris
currently does not expect to obtain the requisite approvals, and consequently be
in a position to effect any exchange of shares and ADSs, prior to June 2003.
Further details about the terms and conditions of the proposed transaction will
be provided as soon as practicable after obtaining the requisite approvals.

Tenaris will not effect any exchange of its shares and ADSs for the Tamsa shares
and ADSs unless it obtains all relevant shareholder and Mexican and U.S.
regulatory approvals. No assurance can be given that the relevant securities
regulators or Tamsa's shareholders' meeting will grant the requisite approvals
within the expected timeframes.

TENARIS URGES INVESTORS TO READ, BEFORE MAKING ANY DECISION, THE REGISTRATION
STATEMENTS, PROSPECTUSES AND ANY OTHER RELEVANT DOCUMENTS THAT WILL BE FILED
WITH THE SECURITIES REGULATORS ONCE THEY BECOME AVAILABLE, BECAUSE THEY WILL
CONTAIN IMPORTANT INFORMATION.

Investors will be able to obtain the documents filed with the SEC, when they
become available, at the SEC's website at www.sec.gov.

This communication does not constitute an offer or solicitation for the sale,
purchase or acquisition of securities of Tenaris or Tamsa in any jurisdiction.

Tenaris is a leading global manufacturer of seamless steel pipe products and
provider of pipe handling, stocking and distribution services to the oil and
gas, energy and mechanical industries and a leading regional supplier of welded
steel pipes for gas pipelines in South America. Organized in Luxembourg,it has
pipe manufacturing facilities in Argentina, Brazil, Canada, Italy, Japan, Mexico
and Venezuela and a network of customer service centers present in over 20
countries worldwide.