Andy Burnham has pledged he will “be there for” Ukraine’s Volodymyr Zelensky and the UK’s support would remain “resolute” under his premiership.
The new Prime Minister indicated that the President of Ukraine would be one of the first foreign leaders he would speak to after replacing Sir Keir Starmer in No 10.
He also indicated plans for a call with US President Donald Trump.
Mr Burnham has little foreign policy experience from his time in government, but he said he had worked with Ukrainian mayors while he was running Greater Manchester.
He said he would support Mr Zelensky personally, as well as offer the UK’s backing to Ukraine.
Mr Burnham told broadcasters: “Those will be my first calls, and I’ll be making very clear later today to President Zelensky that there is no change.
“I will be with him 100 per cent as Keir Starmer has been, and Keir has done really quite an incredible job in not just backing Ukraine but being there in a personal way.
“And I will be absolutely there for him in the same way.
“I’ve worked with Ukrainian mayors over the last few years. I’ve built a network of support for Ukrainian mayors. I take all of that experience into my new role, and President Zelensky will be left in no doubt whatsoever that Britain’s support is steadfast.
“It is resolute. It will be there for him and I will be there for him personally too.”
Mr Burnham used his first speech as Prime Minister in Downing Street to promise to take power out of Westminster and give the public greater control over “life’s essentials”.
Speaking without the lectern used by his predecessors, Mr Burnham said he would set out to help address the cost-of-living squeeze.
In his first promise as Prime Minister, he said he would “end rough sleeping in our country”.
Mr Burnham, who was met with cheers by supporters in Downing Street, said: “I am acutely conscious that I am the sixth person in the last 10 years to walk up this street, the seventh prime minister since 2016, making this a moment for reflection and new resolution.
“It requires my generation of politicians to raise our game and rise to the new challenge.
“Britain needs to show the world that we can regain our stability once again.”
He concluded his first speech as Prime Minister by urging people to “pull with me” to “build a new national sense of unity, of common purpose and positivity”.