Boris Johnson has arrived in Kyiv on the second anniversary of the Russian invasion and said that Ukraine “must win” the war.
The former Prime Minister joined several dignitaries in visiting the capital on Saturday to offer support to President Volodymyr Zelensky.
Mr Johnson tweeted: “On this grim second anniversary of Putin’s invasion I am honoured to be here in Ukraine.
“With their indomitable courage I have no doubt that the Ukrainians will win and expel Putin’s forces - provided we give them the military, political and economic help that they need.”
Rishi Sunak has also pledged to do "whatever it takes" to help the Kyiv cause and released a video with high production values on Saturday.
“On this grim anniversary we must renew our determination,” Mr Sunak said to camera. “And so we are going further with our support.”
He has pledged £250 million towards the production of artillery shells - the biggest single package of support so far.
Mr Sunak added: "This is the moment to show that tyranny will never triumph and to say once again that we will stand with Ukraine today and tomorrow.
"We are prepared to do whatever it takes, for as long as it takes, until they prevail."
British defence secretary Grant Shapps there will be "fatal" consequences if western countries give up on Ukraine.
Speaking to BBC Breakfast on the second anniversary of Russia's full-scale invasion, he said: "We can't have a dictator walk into a democratic neighbour and not stop them and then expect it to end there. It won't end there.
"We've seen this before in Europe. They'd carry on, and not only that, it sends a terrible message to autocrats wherever they are around the world."
Mr Shapps said other regimes would be "looking at this and saying, does the west just get bored after a couple of years?"
"And if we do, that will be fatal because they'll just carry on doing this elsewhere."
