Crimea's parliament voted unanimously to join the Russian Federation.

The pro-Russian authorities in the autonomous Ukrainian region have asked Russian President Vladimir Putin to consider the request, which will be put to a referendum on March 16.

"This is our response to the disorder and lawlessness in Kiev," regional MP Sergei Shuvainikov said .

"We will decide our future ourselves."

At the same time the mayor of Crimean port city Sevastopol said the city would not take part in Kiev's presidential election on May 25.

Alexei Chaly, who was elected to the newly created position of chairman of Sevastopol's executive committee by a rally on February 23, said: "Sevastopol refuses to take part in an election imposed by the illegitimate authorities."

Crimea's new leader Sergei Aksyonov said his government was in regular contact with Russian officials.

Speaking at Crimea's government meeting late on Wednesday, Mr Aksyonov said the strategic peninsula was fully under the control of riot police and security forces joined by about 11,000 "self-defence" troops.

Ukraine's rump government in Kiev responded sharply that it did not recognise the leadership in Crimea and emphasised that as far as it was concerned, Crimea could not legally vote to leave Ukraine.

A spokeswoman for acting president Olexander Turchynov said those in charge in Crimea were "forced to work under the barrel of a gun and all their decisions are dictated by fear and are illegal."

Meanwhile, the US Congress rushed to slap sanctions on Russia, hoping that Europe would follow its lead.

The White House imposed visa restrictions on Russians and Crimeans who are "threatening the sovereignty and territorial integrity of Ukraine."

And President Barack Obama signed an executive order authorising sanctions against "individuals and entities responsible for activities undermining democratic processes or institutions in Ukraine."

Nato's 28 member states decided on Wednesday to suspend a joint mission with Russia, as well as planned civilian and military meetings.

But, while EU foreign ministers have threatened Russia with "targeted measures," the rhetoric in Brussels has been far more cautious than in Washington.