The majority shareholder of Yukos, the Russian oil giant whose main subsidiary was sold to an unknown bidder yesterday, has warned that it will sue for as much as $100bn (€75bn) the new owner and any banks that provide it with finance.

Group Menatep, which owns 53% of Yukos, is today trying to establish the precise ownership of Baikal Finance Group, which emerged as the shock winner of a $9.37bn auction of Yuganskneftegaz, Yukos's biggest asset.