Maxim Barsky, who resigned last year as deputy chief executive of Anglo-Russian oil firm TNK-BP after failing to win BP's support to become CEO, will return as an adviser, two sources close to TNK-BP said on Tuesday.

A third source close to Russia's No.3 oil firm said the role might ultimately pave the way for Barsky to take the top job at TNK-BP, where a boardroom feud led to the resignation of shareholder Mikhail Fridman as CEO on Monday.

The first two sources played down the prospect of Barsky taking the top job, however, saying BP remained cool towards him.

A TNK-BP spokesman declined to comment.

Sources close to both companies say the latest outbreak of hostilities is likely to precipitate an end to the fractious but lucrative relationship that has spanned more than a decade, with a buyout by Rosneft of the Alfa-Access-Renova (AAR) group that represents the Russian shareholders, the most likely outcome.

Meanwhile, Fridman's departure is the most dramatic in a series of potentially destabilising events at TNK-BP which, a source close to one shareholder said, is designed to "rock the boat so that somebody gets out."

Under their shareholder's agreement, BP has the right to nominate the chief executive of TNK-BP. BP's candidate then requires board approval to take up the post.

The board is currently short an independent director, raising issues of quorum for some key votes.

Former German Chancellor and another independent, mining industry veteran James Leng, walked out earlier this year and only one has been replaced.

In addition to TNK-BP Barsky has been involved in less prominent Russian companies, from a Siberian producer and refiner which later merged with Alliance Oil to Pechora LNG, a modestly-sized gas extraction and liquefaction project on Russia's Barents Sea coast which has caught the eye of Gazprom and China's CNOOC.

More recently, he bought a stake and became the CEO of Matra , a London listed exploration and production company, and said it would focus on acquisitions of acreage in Russia and Latin America.

A Russian newspaper report said this week that AAR could club together with Matra to buy a Spanish exploration and production company with projects in Mexico and Colombia, among other Latin American countries.