The deployment of what Russia called a peacekeeping operation in eastern Ukraine is "nonsense" and Moscow's recognition of the breakaway regions as independent is part of its pretext for war, the United States told the UN Security Council on Monday.

The consequences of Russia's actions "will be dire - across Ukraine, across Europe, and across the globe," US Ambassador to the United Nations, Linda Thomas-Greenfield, told the emergency meeting of the 15-member council.

Tensions between Moscow and Western capitals are high following weeks of United States accusations that Russia has deployed up to 150,000 troops near Ukraine's borders for an invasion. Russia has denied it wants to invade Ukraine and accuses the West of hysteria.

Russian President Vladimir Putin on Monday officially recognised the two breakaway regions - the self-proclaimed Donetsk People's Republic and the Lugansk People's Republic - as independent, defying Western warnings that such a step would be illegal and wreck peace negotiations.

"President Putin has torn the Minsk Agreement to shreds. We have been clear that we do not believe he will stop at that," said Thomas-Greenfield, referring to the agreements of 2014 and 2015 that aimed to end conflict between the Ukrainian army and Russian-backed separatists in eastern Ukraine.

Putin also on Monday ordered the deployment of Russian forces to the Donbass region in eastern Ukraine "keep the peace".

"We remain open to diplomacy for a diplomatic solution, however, allowing new bloodbath in the Donbass is something we do not intend to do," Russia's UN Ambassador Vassily Nebenzia told the Security Council.

Ukraine called for the Security Council to meet after Russia's recognition of the two breakaway regions on Monday. Eight council members, including the United States, Britain and France, backed Kyiv's request.

It was the third Security Council meeting on Ukraine in as many weeks. The body has met dozens of times to discuss the Ukraine crisis since Russia annexed Ukraine's Crimea region in 2014. It cannot take any action because Russia is a veto-power along with France, Britain, China and the United States.

UN Secretary-General Antonio Guterres believes Russia has violated the territorial integrity and sovereignty of Ukraine with its decision to recognise eastern Ukraine as independent entities, a U.N. spokesman said.

UN political affairs chief Rosemary DiCarlo told the Security Council the United Nations regretted Russia's order to deploy troops into eastern Ukraine on a reported "peacekeeping mission."