The two sides admitted yesterday to major differences over strategy that could hit production.

In a statement, TNK-BP said it wanted to expand abroad, even if its foreign acquisitions competed with existing BP business. It also deman­ded a better balance between Russian and foreign staff at the company.

The move came after TNK-BP chief executive Robert Dudley said shareholders disagreed on investment and asset sales in Russia. BP shares fell 13.5p to 616.5p.

It is believed BP is keen to reinvest money in developing TNK-BP, while the Russians want to retain cash because they face mounting pressure to sell their stake to one of the state-owned energy companies, Gazprom or Roseneft. The cash would increase the 50 per cent stake’s value.

Dudley claimed a TNK-BP shareholder had been involved in incorrect visa applications for 148 specialist workers in an attempt to lower the number of foreigners in TNK-BP.

BP said it fully supported Dudley.