US President Barack Obama will meet this week with Ukrainian Prime Minister Arseniy Yatsenyuk, the White House said on Sunday, in a prominent show of US support for Ukraine's fledgling new government.

Vice President Joe Biden cut short his trip to Latin America, nixing a planned stop in the Dominican Republic so that he can attend Wednesday s meeting, an assistant to Biden said. Biden had been the White House's prime point of contact with Ukraine's president, Viktor Yanukovich, before he fled to Russia last month following violent clashes in the capital Kiev.

Obama's White House meeting with Yatsenyuk will focus on options to peacefully resolve Russia's military invention in the Ukrainian region of Crimea, the White House said, adding that the resolution must respect Ukraine s sovereignty and territorial integrity.

By inviting Yatsenyuk, whose government Russian President Vladimir Putin alleged took power by way of an unconstitutional coup, the US is also sending a clear signal to Moscow that the US considers Yatsenyuk to be Ukraine's legitimate leader - at least for the time being.

The announcement came as the Kremlin was beefing up its military presence in Crimea ahead of a planned March 16 referendum on whether Crimea should break away from Ukraine and join Russia. Putin defended the drive as in keeping with international law, but Yatsenyuk vowed not to relinquish "a single centimetre" of his country's territory. Obama has warned that the vote would violate international law.

Vacationing with his family over the weekend in Key Largo, Florida, Obama on Saturday spoke individually with British Prime Minister David Cameron, Italian Prime Minister Matteo Renzi and French President Francois Hollande, and collectively with the presidents of Lithuania, Latvia and Estonia. The three Baltic nations are former Soviet republics and now are Nato members. Both Latvia and Estonia have sizable ethnic Russian minorities.