Robert Dudley has been running TNK-BP from outside Russia
BP says it is to appeal against the decision of a Russian labour court to bar the chief executive of its troubled joint venture TNK-BP from the country.
US-born Robert Dudley had left Russia last month when his work permit was not renewed, but has been continuing to work as CEO from outside the country.
Russian shareholders have been seeking to oust Mr Dudley from his post.
BP said it was "disappointed" by the decision and that Mr Dudley would stay in his post during the appeal process.
"Robert Dudley remains CEO pending completion of an appeal process. He has BP's full support," the firm said.
"We believe this is clearly a further example of administrative activity orchestrated by the other shareholders in TNK-BP."
The UK and Russian shareholders of TNK-BP, which is half owned by Russian billionaire group AAR, have disagreed over the firm's management.
Mr Dudley has said "sustained harassment" had prompted him to leave Russia temporarily.
But Russian shareholders say Mr Dudley has not been running the company in the interests of all those involved.
They insist that removing him as chief executive of TNK-BP is their only goal, and reject the idea that they want to control the joint venture.
BP has already removed about 150 of its foreign specialists from the country.