Shearman & Sterling and Cleary Gottlieb Steen & Hamilton have taken leading roles in what could become the largest-ever international arbitration case – a claim against the Russian Federation that could amount to as much as $100bn (£50bn).

The claim, which is due to go before the Permanent Court of Arbitration tribunal in The Hague in November this year, relates to the bankrupt Yukos Oil Company and sees Shearman advising Yukos’s majority shareholders, GML (formerly Group Menatep), with Cleary taking a role advising the Russian Federation.