The decision by the upper house of parliament takes immediate effect - and it could presage a broader attack on Ukraine.

It comes as Russia said it was evacuating its diplomatic personnel from Ukraine because they had received threats.

Mr Putin said the crisis could be resolved if Kyiv recognized Russia's sovereignty over Crimea, the Black Sea peninsula that Moscow annexed from Ukraine in 2014; renounced its bid to join NATO; and partially demilitarized.

White House declares Russian activity in Donbas an 'invasion' - latest Ukraine updates

Ukraine calls up military reservists

In response, Ukrainian President Volodymyr Zelenskyy announced he was calling up some of the country's military reservists, but said there was no need for a full military mobilisation.

On Monday, Moscow recognised the independence of Russian-backed rebel regions in eastern Ukraine.

Some Western leaders have said Russian troops had moved into Ukraine's east - and the US called it an "invasion".

Russia said its recognition of independence for areas in eastern Ukraine extends to territory held by rebels before it was reclaimed by Ukrainian forces.

Kremlin spokesman Dmitry Peskov said Russia recognized the rebel regions' independence "in borders that existed when they proclaimed" their independence in 2014.

Ukrainian forces reclaimed control of large part of the regions during a nearly eight-year conflict.

Ukraine key developments:

• UK targets five Russian banks and three oligarchs with sanctions
• EU sanctions Russian MPs who voted in favour of recognition
• White House refers to Russian troop deployments as an 'invasion'
• Ukrainian president considering breaking off diplomatic ties with Russia
• Germany halts approval of Nord Stream 2 gas pipeline

Russia planning 'full-scale' attack, NATO says

In Brussels, NATO secretary general Jens Stoltenberg said Russia is planning for a "full-scale" attack on its neighbour.

"Every indication is that Russia is continuing to plan for a full-scale attack of Ukraine," he told a news conference.

However, it was unclear how large the Russian troop movements were. Ukraine and its allies have long said Russian troops are already fighting in the region, though Moscow denies those allegations.

Moscow claims deployment is a 'peacekeeping' mission

The upper house's decision allows Mr Putin to deploy Russian military forces to the two separatist-held regions in eastern Ukraine in what Moscow has called a "peacekeeping" mission.

"By approving the use of the armed forces abroad, we assume they will be peacekeeping forces - forces designed to maintain peace and stability in the (self-proclaimed east Ukrainian) republics," Valentina Matvienko, the upper house's speaker, said before the vote.

As Russian MPs met to discuss the vote, the Kremlin announced Mr Putin had ratified friendship treaties with the two breakaway republics - a move Russia says allows it to build military bases there as well as deploy troops, agree a joint defence posture and tighten economic integration.

EU to sanction Russian officials over Ukraine actions

The 27 European Union nations have unanimously agreed an initial set of sanctions targeting Russian officials over their actions in Ukraine, France's foreign minister has said.

EU foreign affairs chief Josep Borrell said the package, which was approved on Tuesday, "will hurt Russia, and it will hurt a lot".

He said the sanctions would affect members of Russia's lower house of parliament and other individuals involved in approving the deployment of Russian troops to rebel-held regions of eastern Ukraine.

President Joe Biden also announced that the US would sanction Russian oligarchs in retaliation for actions against Ukraine, before warning of further measures.

The move came after the UK issued sanctions targeting five Russian banks and three oligarchs, freezing their UK assets and banning travel to Britain.

Read more:
What will happen if Vladimir Putin chooses all-out war?
How big are Russia and Ukraine's militaries?
Can Moscow withstand more sanctions?

Ukraine considers cutting diplomatic ties with Russia

Meanwhile, Ukrainian President Volodymyr Zelenskyy has said he will consider breaking diplomatic ties with Russia. Kyiv also recalled its ambassador in Moscow.

It comes amid an ongoing crisis in the region, with Western powers bracing for a Russian invasion for weeks after it massed an estimated 150,000 troops on three sides of Ukraine.