U.S. Secretary of State John Kerry is meeting his Russian counterpart for likely highly contentious talks amid continuing tensions over Ukraine and American calls for a full probe into the murder of a prominent opposition figure in Moscow.

Kerry and Russian Foreign Minister Sergey Lavrov were to meet in Geneva on Monday, less than a week after Kerry told Congress that Russian officials have lied to his face about Moscow's role in Ukraine.

U.S. officials point out that Kerry did not specifically accuse Lavrov of lying to him. They say he was referring to public statements and media reports.

The meeting comes as the U.S. and its European allies contemplate additional sanctions on Russia for Ukraine. It also follows Friday's murder near the Kremlin of Russian opposition leader Boris Nemtsov.