When BP chief executive Tony Hayward met Mikhail Fridman in a Prague hotel at the end of July, the pressure on BP’s holding in its TNK-BP Russian oil venture had reached fever pitch.

Just days earlier, Robert Dudley, the BP-appointed chief executive, had been forced to leave Russia, citing a campaign of harassment and legal claims that threatened to see him suspended from his post, while he had also failed to get his visa renewed. That same week, a frustrated BP had withdrawn its remaining specialists from the venture and accused its Russian partners of orchestrating a wall of administrative pressure against its foreign staff in order to wrest control away from the British company.