BP’s bitter battle with the four billionaires who control half of its Russian joint venture has escalated to new heights, with the drama poised to move to a British courtroom.

The oil giant is suing its Russian partners in the High Court in London over a $360m (£180m) tax claim.

The claim, which was lodged last Monday, alleges that BP is owed the sum under the terms of an agreement that was struck at the creation of the TNK-BP joint venture in 2003.

It also alleges that BP has made three separate attempts to reach an agreement on the issue, the first of which was made more than 15 months ago.

The four billionaires - Mikhail Fridman, Viktor Vekselberg, Leonard Blavatnik and German Khan - plan to fight the claim. A spokesman for their holding company, AAR, also described the figure quoted in the writ as “inflated”.

BP has been at war with the four billionaires since late last year, after disagreements over strategy and the dividend policy descended into a battle for control of the business.

The row has coincided with an assault on TNK-BP by various branches of the Russian state.

A dispute over visas for foreign workers at the subsidiary is likely to see some TNK-BP employees deported in the next few days.

The prime minister, Gordon Brown, is expected to raise the TNK-BP row at this week’s G8 meeting. The German and American delegations are also believed to be planning to address the matter, along with the broader issue of Russia’s relations with the business world in general.

A further legal row over the future of TNK-BP is expected to erupt in Moscow tomorrow.

At a meeting of the TNK-BP management board, Vekselberg will call a vote to demand the sacking of Robert Dudley, the chief executive of the joint venture.

Vekselberg is destined to lose the vote, because BP has more votes on that board. If that is the outcome, the four billionaires have threatened to raise a legal action against the three BP-appointed directors who sit on the management board: Steve Ridlington, Steve Truman and Peter Henshaw.

The billionaires will claim that the three men have breached their fiduciary duties by failing to sack Dudley. The legal actions are expected to be raised in Moscow, London and the British Virgin Islands, where the holding company is registered.

A meeting of the full TNK-BP board is scheduled to take place on Friday. If it goes ahead, it will be the first time both halves of the company have formally convened since last November.

Sources close to the Russian camp believe there is an outside chance of a settlement being agreed at the meeting.

However, analysts believe that any deal agreeable to the Russians would involve BP agreeing to extend TNK-BP’s operations into other parts of the world.

BP is not thought to be willing to agree to such a move, which would conflict with the oil giant’s existing international plans.

Oil-industry sources believe that a final settlement of the dispute will involve Gazprom or Rosneft, Russia’s two state oil companies, buying all or part of the business.

The four billionaires have repeatedly denied that they want to sell out. TNK-BP now accounts for a quarter of BP’s oil reserves globally.

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