Boris Johnson has warned Vladimr Putin he faces "bitter and bloody" resistance from the people of Ukraine if Russia launches an invasion of its neighbour.
The prime minister said he will urge the Russian president to “step back from the brink” when the pair hold talks on the crisis this week.
He said a Russian invasion of Ukraine would be “an absolute disaster for the world”.
The prime minister is expected to visit the region shortly, as tensions remain high over the Russian military build-up on the border with Ukraine.
Speaking to reporters during a visit to Tilbury in Essex, Mr Johnson said: “What I will say to President Putin, as I have said before, is that I think we really all need to step back from the brink.
“I think Russia needs to step back from the brink.
“I think that an invasion of Ukraine - any incursion into Ukraine beyond the territory that Russia has already taken in 2014 - would be an absolute disaster for the world, and above all it would be a disaster for Russia.”
Mr Johnson said that any Russian invasion would be “bitterly and bloodily resisted” by the Ukrainian people.
