Boris Johnson will chair a Cobra meeting this morning to discuss the UK's reaction to the Ukraine crisis and put in place "significant" sanctions for Russia, Downing Street has said.
The meeting, which is scheduled to take place at 6.30am, will be used to "coordinate the UK response", including agreeing a "significant package of sanctions to be introduced immediately", according to a No 10 spokesperson.
It comes after Foreign Secretary Liz Truss said the UK will announce new sanctions against Russia later today "in response to their breach of international law and attack on Ukraine's sovereignty and territorial integrity".
The Kremlin has said President Vladimir Putin is ordering Russian forces to "maintain peace" in eastern Ukraine.
According to reports, the peacekeeping operation is in the two regions of Donetsk and Luhansk which the Russian president earlier said he would recognise as breakaway republics.
A No 10 spokesperson said: "The Prime Minister will chair a COBR at 0630 tomorrow morning to discuss the latest developments in Ukraine and to coordinate the UK response including agreeing a significant package of sanctions to be introduced immediately."
Johnson has told Ukrainian president Volodymyr Zelenskyy that he believes a Russian invasion is "a real possibility in the coming hours and days".
A Downing Street spokesperson said: "Prime Minister Boris Johnson spoke to Ukrainian President Volodymyr Zelenskyy this evening to discuss the deteriorating situation in and around Ukraine.
"Outlining his grave concern at recent developments in the region, the Prime Minister told President Zelenskyy that he believed an invasion was a real possibility in the coming hours and days.
"The Prime Minister strongly condemned the Kremlin's decision today to recognise Luhansk and Donetsk as independent states, and said the move made the Minsk agreements and process unworkable.
"He added that the UK was already engaging with partners on the issue and said the UK would raise it at the United Nations Security Council and Organisation for Security and Co-operation in Europe in the coming days."
Putin told Russia's defence ministry to deploy troops into the two regions to "keep the peace" in a decree issued shortly after he announced recognition for Russia-backed separatists there, drawing US and European condemnation and vows of new sanctions.
It was not immediately clear whether the Russian military action was the start of an invasion of Ukraine that the United States and its allies have warned about for weeks. There was no word on the size of the force Putin was dispatching, when they would cross the border and exactly what their mission would be.
In a lengthy televised address, Putin, looking visibly angry, described Ukraine as an integral part of Russia's history and said eastern Ukraine was ancient Russian lands and that he was confident the Russian people would support his decision.
Russian state television showed Putin, joined by Russia-backed separatist leaders, signing a decree recognising the independence of the two Ukrainian breakaway regions along with agreements on cooperation and friendship.
Defying Western warnings against such a move, Putin had announced his decision in phone calls to the leaders of Germany and France earlier, both of whom voiced disappointment, the Kremlin said.
Moscow's action may well torpedo a last-minute bid for a summit with U.S. President Joe Biden to prevent Russia from invading Ukraine.
