Boris Johnson has warned an invasion of Ukraine could take place within 48 hours as he urged Vladimir Putin to step back from the “edge of a precipice”.

The Prime Minister said “serious preparations” were being made for a Russian invasion, with around 130,000 troops massed on the borders of Ukraine.

In a message to European allies, Mr Johnson said the world needed to demonstrate the political and economic cost an invasion would have on Russia, including by ending reliance on its gas.

On a visit to Rosyth shipyard in Scotland, he said: “This is a very, very dangerous, difficult situation, we are on the edge of a precipice but there is still time for President Putin to step back.”

He called for more dialogue and urged Russia to avoid a “disastrous” invasion.

Reports based on US intelligence assessments have suggested an invasion could be launched as soon as Wednesday.

The Prime Minister said: “The signs, as you’ve heard from (US) President (Joe) Biden that they’re at least planning for something that could take place as early as in the next 48 hours.

“That is extremely concerning.”

The Prime Minister said “the world needs to learn the lesson of 2014” when not enough was done to move away from Russian gas and oil following the Russian action in eastern Ukraine and the annexation of Crimea.

“What I think all European countries need to do now is get Nord Stream out of the bloodstream,” he said.

“Yank out that hypodermic drip feed of Russian hydrocarbons that is keeping so many European economies going.

“We need to find alternative sources of energy and we need to get ready to impose some very, very severe economic consequences on Russia.”