Boris Johnson has compared Volodymyr Zelensky's leadership of Ukraine to the war-time exploits of Sir Winston Churchill.
The Prime Minister said he believed "Churchill would have cheered and probably have wept too" when the Ukrainian President insisted he needed "ammunition, not a ride" out of Kyiv when the Russian invasion was began in February.
Mr Johnson's comments came during a ceremony in 10 Downing Street in which he presented Mr Zelensky, who appeared via video link, with the Sir Winston Churchill Leadership Award.
Members of the Churchill family and the International Churchill Society attended the ceremony.
Mr Zelensky said: "This is my extreme honour to receive this award for leadership.
"Ukraine was not left alone after February 24, we had those who were helping us, who remembered in the darkest times what is honour, and who have not thought of quitting the struggle – I’m talking about you Boris," he added.
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"This award is yours as well and this is the manifestation of our joint leadership of Ukrainians, Britons and all those who will not give their freedom away to any tyrants."
In March, Mr Zelensky invoked British war leader Sir Winston Churchill in an emotional address to MPs, vowing to fight invading Russian troops in the air, sea and on the streets.
Mr Johnson recalled receiving the call from Mr Zelensky on February 24 to confirm the "insanity had broken out" and that Russian tanks were "surging across the frontier".
"In that moment of supreme crisis, you faced a test of leadership that was, in its way, as severe as Churchill's challenge in 1940,” he said.
Mr Johnson added: "Your defiance, your dignity, your unfailing good humour has moved millions, and as you stand against barbarism, you've become a symbol of the heroism of the Ukrainian people.
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"You've addressed so many parliaments that I've lost count and you brought both sides of the House of Commons to their feet, something that Churchill would surely have envied, and I can imagine his spirit walking with you, silently urging you on, encouraging you through every ordeal, jabbing the way ahead with his walking stick - you have already quoted this phrase earlier in the article and perhaps marvelling at your superb contempt for danger, something that he himself understood.
"And like Churchill you've understood that you are not yourself the lion, the Ukrainian people are the lion, but you have been called upon to give the roar, the roar of freedom against tyranny, of good against evil, of light against darkness.
"And you have delivered that roar magnificently and that's why it was such a huge stroke of good fortune that you should have been in office at this time of crisis for Ukraine and the world.
"And inspired by your leadership, I know not just that Ukraine can win but Ukraine will win, and when that day comes, as it will, Ukraine will rise and take its place, as a free sovereign and independent nation."
A bust of Sir Winston Churchill was presented to Ukraine's ambassador to the UK, Vadym Prystaiko.