Tensions between the joint owners of TNK-BP, the Anglo-Russian oil group, heightened last night amid signs that the billionaire oligarchs who own half of Russia's third-largest crude producer were increasing their grip on the business.

Reports yesterday said that TNK-BP would dismiss 390 managers and close 200 vacancies at its Moscow headquarters, representing 19 per cent of its staff. A spokesman for TNK-BP in Moscow declined to comment on the number of staff affected, but confirmed that the group was pursuing a cost-cutting strategy.

The cuts run counter to the aims of BP, which stated only four months ago that it wanted to bolster its Russian joint venture.

TNK-BP lost 148 seconded employees from BP, mostly technical experts and engineers, in April when the row over ownership spilled into a dispute regarding work permits and visas.

On July 29, Tony Hayward, BP's chief executive, said that BP wanted to boost investment in TNK-BP by 20 per cent in 2008. He also said that BP was “committed to” increased investment in the Russian oil and gas industry, while AAR, the vehicle owned by Viktor Vekselberg, Mikhail Fridman, German Khan and Leonard Blavatnik that controls 50 per cent of TNK-BP, was not. “Not all of the other shareholders support this investment,” he said at the time.

A spokesman for BP in London said that the latest decision to cut staff was a matter for TNK-BP's management board and reflected falling oil prices rather than a strategy disagreement.

Robert Dudley formally stepped down as chief executive of TNK-BP yesterday, to be temporarily replaced by Tim Summers, the chief operating officer. Mr Dudley had been appointed by BP.

The new chief executive is expected to be Denis Morozov, the former chief executive of Norilsk Nickel, another Russian industrial group. He is expected to be nominated at a board meeting on December 11.

The details of the new corporate structure are still being hammered out, but, in a statement released yesterday, Mr Dudley said that he was departing TNK-BP “after more than five challenging and immensely satisfying years building” what he described as a “unique and progressive” Russian oil company.

In an e-mail to TNK-BP staff, which was seen by The Times, Mr Dudley acknowledged that the company's problems were not over. “Some very testing times lie ahead,” the American executive said. “The company is moving towards a new governance model and will soon have a new management team. There will be less reliance on BP experts and senior international leadership. External conditions will likely be adverse.”

In response, he urged staff to offer their “full and enthusiastic support” for his replacement and his new management team.

Mr Dudley is expected to return to the United States to be with his family rather than go back to work for his former employer.

— The price of oil slipped by more than $5 yesterday to $49 a barrel after Opec, the oil exporters’ cartel, opted at the weekend to wait until later this month to cut production in defence of prices. US crude settled down $5.15 at $49.28 a barrel, the lowest settlement since May 2005.

The price of a barrel of London Brent crude was $5.52 lower at $47.97. The drop in prices came as Abdalla el-Badri, the secretary-general of Opec, said that the oil producers’ organisation would consider an output cut of between one million and 1.5 million barrels per day at a meeting in Algeria on December 17.

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