BP has a stake of just under 20 percent in Russian state-controlled oil major Rosneft and generates a quarter of its oil output from Russian oil fields. It is also one of the biggest buyers of Russian oil.

On Wednesday, U.S. President Barack Obama imposed the toughest sanctions yet on Russia, targeting companies closest to Russian leader Vladimir Putin over what Washington says is Moscow's failure to curb violence in Ukraine.

(Reporting by Dmitry Zhdannikov; editing by Jason Neely)

Stocks treated in this article : Exxon Mobil Corporation, Rosneft' NK OAO, BP plc