British Prime Minister Boris Johnson said "despicable attacks against civilians" in Bucha and Irpin near Kyiv were evidence that Russia was committing war crimes in Ukraine, and that Britain would step up sanctions and military aid in response.
"I will do everything in my power to starve (Russian President Vladimir) Putin's war machine," Johnson said in a statement on Sunday.
"We are stepping up our sanctions and military support, as well as bolstering our humanitarian support package to help those in need on the ground."
Russia's defence ministry denied Ukrainian allegations of attacks on civilians, saying footage and photographs showing dead bodies in Bucha were "yet another provocation" by Kyiv.
