British Prime Minister Boris Johnson described the situation on Ukraine-Russia border “very very dangerous” on Monday, Sky News reported.

The Prime Minister will hold a full meeting of the government's COBRA emergency committee on Tuesday to discuss the UK's response to the current situation in Ukraine.

Johnson said there is "pretty clear" evidence that Russia is planning an invasion of Ukraine, with some reports saying US intelligence believes military action could begin as early as this Wednesday.

“You've got about 130,000 troops massing on the Ukrainian border. There's all sorts of other signs that show that there are serious preparations for an invasion,” he said.

However, Johnson added that Russian President Vladimir Putin "still has time" to "step back". "We're urging is for everybody to engage in dialogue for a conversation to take place and for the Russians to avoid … a disastrous mistake for Russia," he said.

Johnson said he was "extremely concerned" about indications that Russia was "planning for something that could take place as early as in the next 48 hours". "What we need to do is make sure that President Putin understands the economic consequences, the political consequences of doing this."

He added that Europe must reduce its energy dependency on Russian resources, and find alternative sources of energy.

“We need to get ready to impose some very, very severe economic consequences on Russia,” he said.