Exhibit 99 Tenaris Announces Sidor Debt Restructuring LUXEMBOURG--June 23, 2003--Tenaris S.A. (NYSE:TS) (Buenos Aires:TS) (BMV:TS) (MTA Italy:TEN), announced today that its associated companies, Consorcio Siderurgia Amazonia Ltd. (Amazonia) and Siderurgica del Orinoco C.A. (Sidor), have reached an agreement with their financial creditors and the Venezuelan government relating to the restructuring of Sidor's and Amazonia's financial debt. Under the terms of the agreements, Sidor's and Amazonia's aggregate financial debt has been reduced from US$1,883 million to US$791 million, certain shareholders of Amazonia have contributed US$133.5 million in cash to a newly created company for the acquisition and capitalization of Sidor's and Amazonia's financial debt, the government of Venezuela has increased its participation in Sidor from 30% to 40.3% and all the guarantees provided by the shareholders of Amazonia with respect to loans made to Sidor have been released and replaced with a security on the fixed assets of Sidor which, together with the pledges on the shares of Amazonia and the shares that Amazonia holds in Sidor, have been placed in trust for the benefit of Sidor's financial creditors and the Venezuelan government. In addition, a portion of Sidor's excess cash (determined in accordance with an agreed-upon formula) will be applied to repay Sidor's financial debt and the remainder will be distributed to the Venezuelan government and the newly created company referred to above. Tenaris's subsidiary, Tubos de Acero de Mexico S.A. (AMEX: TAM) (BMV:TAMSA) (Tamsa), has participated in this restructuring agreement by making an aggregate cash contribution (mainly in the form of new subordinated convertible debt) of US$32.9 million to the newly created company and by capitalizing in Amazonia convertible debt previously held by Tamsa in the amount of US$18.0 million plus accrued interest. Tamsa's indirect participation in Amazonia has increased from 14.1% to 14.5% and may further increase up to 21.2% if and when all of its new subordinated convertible debt is converted into equity. Sidor's remaining financial debt is now made up of three tranches, one of US$350.5 million to be repaid over 8 years with one year of grace, one of US$26.3 million to be repaid over 12 years with one year of grace and the remaining tranche of US$368.6 million, to be repaid over 15 years with one year of grace. In addition, Sidor's commercial debt with certain Venezuelan government-owned suppliers has been fixed in the amount of US$45.4 million, to be repaid over the next five years. As a result of this restructuring, Tenaris, through its subsidiary, Tamsa, has retained a participation in a business with competitive costs and an improved financial structure that will continue to supply the steel bars used as raw material for Tenaris's seamless pipe operations in Venezuela. 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. CONTACT: Tenaris Gerardo Varela, 888/300-5432 www.tenaris.com