Directors at BP PLC's (BP) Russian joint venture TNK-BP Ltd. will at a board meeting later Friday not only discuss the possibility of legal action against the U.K. oil major but also against its Russian billionaire partners, a person familiar with the matter said.

The allegations against both shareholders signal that BP and its Russian partners in TNK-BP--known as the Alfa-Access-Renova consortium, or
AAR --are keeping up pressure on each other amid reports they may settle a number of legal disputes out of court.

Earlier this year,
AAR blocked BP's proposed $16 billion share swap and Arctic exploration deal with Russia 's state-owned OAO Rosneft (ROSN.RS). They argued that BP violated the TNK-BP shareholder agreement, which states any new business opportunities must be offered to the joint venture first.

At Friday's board meeting, TNK-BP directors will hear recommendations from external lawyers on whether to sue BP for damages as a result of the
U.K. firm's deal with Rosneft independently of TNK-BP. A vote on the matter is expected to take place in 2012.

A person familiar with the matter said that in addition, the board will discuss potential legal claims against
AAR for failing to notify the joint venture about its knowledge of the planned BP-Rosneft deal.

"Withholding of such information may constitute a breach of the director's duties to the company and can be the ground for potential claims to
AAR nominated directors," the person said.

Also, the board will discuss the possibility of legal action against Viktor Vekselberg--a Russian TNK-BP shareholder--for failing to offer the joint venture some oil and gas assets held by his holding company Renova Group.

Meanwhile, arbitration proceedings launched to block the BP-Rosneft deal are still under way, with a tribunal likely to formally rule on whether BP breached the shareholder agreement by agreeing the tie-up with Rosneft.

BP said it hasn't breached the TNK-BP shareholder agreement and that TNK-BP incurred no loss as a result of the failed deal with Rosneft.
AAR declined to comment.