May 17, 2006 — Mittal Steel Co. NV announced that the information document relating to its offer for Arcelor shares and convertible bonds has been approved by the Luxembourg Commission de Surveillance du Secteur Financier, the Belgian Commission Bancaire, Financiere et des Assurances and the French Autorite des marches financiers.

Approval of Mittal’s information document follows coordination among the European regulators. The document is expected to be approved by the Spanish Comision Nacional del Mercado de Valores in the near future.

The Dutch Autoriteit Financiele Markten has also approved the share listing prospectus prepared for the issuance of new Mittal Steel class A common shares in connection with the Offer and for the admission of such shares to trading on Euronext Amsterdam, Euronext Brussels, Euronext Paris, the Luxembourg Stock Exchange and the Spanish Stock Exchanges. This share listing prospectus is passported into Luxembourg, Belgium, France and Spain under EU prospectus legislation.

The acceptance period for the Offer in Luxembourg, Belgium and France will start on May 18, 2006 (the date on which the information document will be published), except in Spain. In Spain, the acceptance period will commence on the date indicated in the Spanish version of the information document expected to be approved by the CNMV. The acceptance period will close 30 business days after it opens (June 29, 2006 for Luxembourg, Belgium and France). The acceptance period for the Offer in the United States will start on the date that the registration statement on Form F-4 currently under review by the SEC is declared effective.

Commenting, Mr. Lakshmi N. Mittal, Chairman and Chief Executive, said, "We are delighted to have today received approval from most of the securities regulators on our offer documentation for our tender offer on Arcelor. Now shareholders will have the opportunity to decide for themselves on the value and merits of our proposal. We remain excited about the prospects of our offer, which is based on very sound industrial logic and provides tremendous value creation potential. We believe that stakeholders in the steel industry appreciate the need for further consolidation and recognize the benefits it can bring in creating a more sustainable operating environment. The Mittal/Arcelor combination would define the model of the future, creating a financially strong, balanced, global market leader, ideally positioned to exploit growth opportunities in a consolidating industry"

Mittal Steel Co. is the world's largest and most global steel company, with operations in sixteen countries, on four continents. Mittal Steel encompasses all aspects of modern steelmaking, to produce a comprehensive portfolio of flat and long steel products to meet a wide range of customer needs. It serves all the major steel consuming sectors, including automotive, appliance, machinery and construction. For 2005, Mittal Steel had revenues of US$28.1 billion and steel shipments of 49.2 million tons.

The company notes that no offer to exchange or purchase any Arcelor shares or convertible bonds has yet been made in The Netherlands or in any jurisdiction other than Luxembourg, France, Spain (subject to subject to approval of the Spanish version of the Information Document by the CNMV), Belgium and the United States. The company further notes that this announcement does not constitute an offer to exchange or purchase any Arcelor shares or convertible bonds, and that such offers will be made only pursuant to an official offer document approved by the appropriate regulators.