US officials have claimed that North Korea is suffering mass casualties on the front lines of Russia’s war against Ukraine, as Biden pushes to send a £1bn boost to Kyiv.White House spokesperson John Kirby told reporters on Friday that thousands of North Korean troops had been killed or wounded in the last week alone.

Volodymyr Zelenskyy said earlier this month that Russia was trying to "conceal losses" of North Korean troops fighting against Ukraine.