Britain said on Thursday there was "very, very strong evidence" of war crimes being committed in Ukraine and that Russian President Vladimir Putin was behind them, but it stopped short of calling him a war criminal.
U.S. President Joe Biden on Wednesday called Putin a war criminal in comments the Kremlin said were "unforgivable".
Asked if Britain was prepared to echo those remarks, British Foreign Secretary Liz Truss told BBC radio:
"There's very, very strong evidence that war crimes have been committed and that Vladimir Putin is behind them."
"It is ultimately a matter for the International Criminal Court to decide who is or isn't a war criminal, and for us to bring the evidence."