Ukrainian President Volodymyr Zelensky said up to 3,000 Ukrainian soldiers have died and as many as 10,000 have been left injured since the invasion began.
He gave the update of between 2,500 and 3,000 deaths in an interview with CNN, in which he also warned about the threat of potential Russian nuclear strike, as we reported earlier.
A month ago, Zelensky estimated that around 1,300 Ukrainian troops had died. But on both occasions, he claimed far more Russian soldiers had been killed.
The BBC has been unable to independently verify these figures, which do not include civilians.
Both sides in the conflict have made frequent claims about the casualties they have inflicted on each other - usually far higher than what their opponent's official count is.