Boris Johnson has announced an additional £175m in UK aid for Ukraine, bringing the total to almost £400m.

The announcement came after the prime minister held talks with counterparts Mark Rutte of the Netherlands and Justin Trudeau of Canada at 10 Downing Street.

Mr Johnson also said that Britain will join the Netherlands and Canada in an international Ukraine support group to co-ordinate the efforts of the global community to provide long-term assistance, and urged other countries to sign up.

Speaking at a press conference alongside Rutte and Trudeau in Downing Street, Mr Johnson said: “After 12 days, it’s already clear that Putin has made a miscalculation.

“He has under-estimated Ukrainians’ resistance, he has underestimated their leader and he has underestimated the unity of the West.

“And we will continue as colleagues to do everything we can to strengthen that unity in the days ahead to ensure that Putin fails in this catastrophic invasion of Ukraine.”

Mr Johnson said the three countries “stand shoulder to shoulder against Russia’s barbaric invasion of Ukraine”.

“In the 12 days since Russia launched this illegal and brutal assault, the world has come together in solidarity with the indomitable people of Ukraine,” he added.

Mr Johnson said it was clear that the friends of Ukraine would have to do more, as Vladimir Putin showed no sign of backing down.

“What’s happening now is that Putin is doubling down,” said the British PM.

“He’s decided that he’s going to continue with an all-out onslaught on centers of habitation in a way that we think is utterly disgusting.

“It’s clear that we’re going to have to do more And as best friends and partners that’s what we’re going to do.”