Cleary Gottlieb Steen & Hamilton has secured a lead role acting for Mittal Steel, the world’s biggest steelmaker, on its 18.2bn (£12.5bn) bid for Luxembourg-based steel giant Arcelor.

Cleary is fielding a heavyweight team out of its Paris office for the deal, which, if it goes ahead, will create a company with a market capitalisation of around $40bn (£22bn).