Crimean city declares itself Russian

The Ukraine city of Sevastopol has declared itself a subject of the Russian Federation, hours after the semi-autonomous parliament of Crimea voted to do the same.

The city, on the Crimean peninsula and home to the Black Sea fleet of the Russian navy, made the announcement late on Thursday.

Meanwhile, US President Barack Obama urged President Vladimir Putin to seek a diplomatic solution to the crisis in Ukraine, in a lengthy telephone call.

In their hour-long conversation, the Russian leader said Moscow-Washington relations should not suffer.

Russian troops have taken de facto control of Crimea following the fall of Ukraine's pro-Moscow president.

The crisis has led to a boycott by many foreign dignitaries of the Sochi Winter Paralympics, which open on Friday.

President Obama stressed to Russia's president that his country's actions in Crimea were a violation of Ukrainian sovereignty, the White House said in a statement.

He said there was a solution available that suited all parties, involving talks between Kiev and Moscow, international monitors in Ukraine and Russian forces returning to their bases.

For his part, President Putin said US-Russian "relations should not be sacrificed due to disagreements over individual, albeit extremely significant, international problems," the Kremlin said.

It was the two leaders' second telephone call concerning Ukraine in less than a week.

The US and EU earlier joined the Ukrainian government in condemning as "illegitimate" an earlier vote by the Crimean parliament to secede from Ukraine, and bring forward a planned referendum on the subject to March 16.

The move was condemned by Kiev as having no basis in law, while the US President Barack Obama said the referendum would violate the Ukrainian constitution and international law.

"Any discussion about the future of Ukraine must include the legitimate government of Ukraine," he said.

However, Rustam Temurgaliyev, the region's deputy prime minister, had earlier said the decree was effective immediately and that Russian soldiers were the only legitimate forces in Crimea. 

"The Ukrainian armed forces have to choose: lay down their weapons, ... accept Russian citizenship and join the Russian military."

"If they do not agree, we are prepared to offer them safe passage ... to their Ukrainian homeland."

Ukraine's Prime Minister Arseniy Yatsenyuk said the vote was "illegitimate", while Oleksander Turchinov, the acting president, said Crimea MPs were working "under the barrel of a gun".

Obama also issued an executive order authorising sanctions  against "individuals and entities responsible for activities undermining democratic processes or institutions in Ukraine.''

He said that Russia's involvement in Crimea constituted "an unusual and extraordinary threat to the national security and foreign policy of the United States".

Meanwhile, the European Union announced that it was to suspend talks with Russia on a wide-ranging economic pact and on a visa deal. It also threatened further sanctions if Russia did not quickly engage in talks to end the crisis.

After a meeting of EU ministers in Brussels, Donald Tusk, Poland's prime minister, said the EU members of G8 had also agreed to suspend preparations for a G8 summit in June in Sochi.