Downing Street has criticised Pete Hegseth for downplaying the role of Nato allies in helping the US with combat operations in Afghanistan, saying Donald Trump’s defence secretary had been wrong to do so.

The direct condemnation came as No 10 more carefully distanced itself from Trump’s increasing willingness to engage with Russia, saying the UK’s backing for Ukraine was “unwavering”.

Making a speech on Saturday, Hegseth, who served as a Minnesota Army National Guard instructor in Afghanistan, said that when he would go to the coalition base in Kabul, “there would be 50 flags at the headquarters”.

He went on: “And it was a beautiful thing to see, 50 different countries contributing to the Nato alliance and the Isaf [International Security Assistance Force] mission there. Except there were maybe five that contributed. It was actually closer to one or two that actually … by the end were actually involved in kinetic operations.

“In fact, the patch ‘Isaf’ – we joked that it meant ‘I Saw Americans Fighting’. Which is sort of a joke but it’s demoralising when you feel like it’s not burden-sharing, it’s actually a burden.”

While almost 2,500 US forces died in Afghanistan, two-thirds of the total death toll, personnel from more than 30 nations died on duty there, including 457 from the UK.

Asked about Hegseth’s comments, Andy Burnham’s official spokesperson said: “Frankly, the facts speak for themselves when it comes to the UK’s and Nato’s contribution to Afghanistan.

“Thousands of British and allied families made huge sacrifices to play their significant part in that war and uphold our values, and more than 450 British personnel never returned.

“Their sacrifice and that of other Nato forces was made in the service of collective security and in response to an attack on our ally. We are incredibly proud of our armed forces, and their service and sacrifice will never be forgotten. And it is wrong to diminish their role.”

The remarks echo an even more direct rebuke to Trump by Keir Starmer in January, when the then PM said the president should apologise for “insulting and frankly appalling” remarks claiming that Nato troops had stayed “a little back, a little off the frontlines” in Afghanistan.

On Ukraine, Trump has recently renewed his criticisms of the Ukrainian president, Volodymyr Zelenskyy, eased sanctions on Russia and limited intelligence-sharing that helps Ukraine counter Russian missile and drone attacks.

Asked about reports that the US president wanted to convene a peace summit involving the US, Russia and China, but not Ukraine, the No 10 spokesperson did not respond directly to that, but made clear the UK’s different approach.

He said: “Our position on Ukraine has been consistent since the conflict broke out, and that is that we want Ukraine to secure a just and lasting peace.”

Pushed on the mooted three-way talks, he said: “Well, obviously that’s a matter for those countries, and obviously for Ukraine to speak for itself.”

The spokesperson added: “Our support for Ukraine is unwavering, and I think you saw that in the prime minister’s meeting with President Zelenskyy last week.”