LONDON (Reuters) - U.S. Secretary of State John Kerry will seek assurances from Russia on Friday that it will not seek to annex Crimea and will address concerns over Ukraine through negotiation, a senior State Department official said before the talks in London.
Kerry meets Russian counterpart Sergei Lavrov later in the day in last-ditch diplomatic efforts to defuse tension between Moscow and the West even as a referendum in Crimea, a Russian-majority region of Ukraine, looked set to proceed on Sunday.
The vote, arranged after mass protests toppled pro-Russian Ukrainian President Viktor Yanukovich, will decide whether Crimea will become part of Russia. Kerry's first stop in London will be a meeting with British Minister David Cameron.
"What we would like to see is a commitment to stop putting new facts on the ground and a commitment to engage seriously on ways to de-escalate the conflict, to bring Russian forces back to barracks, to use international observers in place of force to achieve legitimate political and human rights objectives," the U.S. State Department official said.
"A commitment to respect and restore the unity, sovereignty and territorial integrity of Ukraine."
Kerry has warned the Kremlin that the United States and the European Union will impose sanctions against Russia as soon as Monday if the referendum goes ahead.
"Crimeans seem bound and determined to go forward with this.
It will not have force of law in Ukraine. We will be interested to hear from Mr Lavrov how Russia sees this as it bears down," the senior official said of the referendum plans.
The official, who briefed reporters ahead of the trip, suggested the United States would offer additional proposals for resolving the tensions, which has brought U.S.-Russian relations to one their lowest points since the Cold War.
So far Moscow has not shown it is ready to seriously engage in a political solution, according to U.S. officials.
"If the Russians choose not to take that course, if President Putin chooses not to avail himself with that opportunity, then as President (Barack Obama) has said there will be costs," the official said.
"We have made clear there is a preferred way to deal with this, which is to begin de-escalating."
The massing of Russian troops on Ukraine's border has concerned Washington and will be raised during the discussion with Lavrov, according to the senior State Department official.
"We are very concerned. This is the second time inside of a month that Russia has chosen to mass large amounts of force on short notice without much transparency around the eastern borders of Ukraine," the official said
"It certainly creates an environment of intimidation, it certainly is destabilizing and that will be one question asked what is meant by this."
The United States has posed several questions to Moscow in a one-page letter that explores whether Moscow would be willing to dampen down tension by withdrawing its forces back to barracks and agreeing to international monitors in Crimea.
Ukraine has made clear it is willing to negotiate with Russia and is prepared to guarantee autonomy for Crimea within Ukraine. The international community has said it will not recognize the outcome of the referendum planned for Sunday.
Crimea has a narrow ethnic Russian majority and many in the province of 2 million people clearly favor rule from Moscow.
Editing by Mark Heinrich