Russia’s Parliament has approved the use of armed force in Ukraine, even as the West warned Moscow not to intervene in the troubled post-Soviet state.

President Vladimir Putin, who is Commander-in-Chief of the Russian armed forces, asked Parliament for permission to use the Russian armed forces to “protect” Russian civilians and military in Ukraine.

Meeting in emergency session on Saturday the Federation Council, the Russian Parliament’s upper house, unanimously granted its “consent for the use of armed forces in Ukraine till normalisation of the situation” in the neighbouring country.

The move came in response to a request of help to “secure peace and calm” in Crimea from the newly appointed pro-Russian Prime Minister of the region.

Sergei Aksyonov said on Saturday that Russian troops from the Black Sea Fleet in Crimea were already guarding vital facilities in the region and helping ensure public order.

“The situation in the autonomous republic of Crimea has been taken under full control,” said Mr Aksyonov, who replaced a centre-appointed head of Crimea after the region rejected the authority of new government in Kiev.

Mr Aksyonov told a cabinet meeting on Saturday that a referendum on greater independence of Crimea from Kiev will be held on March 30, almost two months earlier than announced on Thursday. Voters will be asked to say yes or no to the question:

“The Autonomous Republic of the Crimea enjoys state independence and is part of Ukraine on the basis of treaties and agreements.”

On Saturday, thousands of demonstrators rallied in Ukraine’s Russian-speaking cities of Donets and Kharkiv in support of the demand to call similar referendums in their regions.

In announcing plans to send more troops to Crimea Mr Putin ignored U.S. President Barack Obama’s warnings of consequences for Moscow’s interference.

“Any violation of Ukraine’s sovereignty and territorial integrity would be deeply destabilising, which is not in the interests of Ukraine, Russia or Europe.” Mr Obama said in a statement from the White House on Friday.

Russia’s lawmakers on Saturday asked Mr Putin to recall the Russian ambassador from the U.S. in protest against Mr Obama’s “threats.”

Ukraine’s Acting President Oleksandr Turchynov accused Russia of trying to annex Crimea as it did in the breakaway regions of Abkhazia and South Ossetia in 2008.

“Russia has launched undisguised aggression against our country,” Mr Turchynov said in a TV address, appealing to Mr Putin to “stop provocations and start negotiations.”

A senior Ukrainian official told local media that 13 Russian transport aircraft carrying nearly 2,000 troops had landed at a military air base near Simferopol.

However, Russia's ambassador to the U.N. Vitaly Churkin said that any Russian military movements in Crimea were within Moscow’s agreement with Ukraine for leasing a Soviet-era naval base in Crimea’s Sevastopol. The Russian envoy rejected a U.S. proposal of a closed-door meeting of the U.N. Security Council on Friday to send an international mediation team to Crimea to help stabilise the situation in the region.