The U.N. human rights office said on Wednesday that it had verified 1,424 civilian casualties since the Ukraine conflict began two weeks ago - 516 killed and 908 injured - but believed the real figures were "considerably higher".
The civilian toll rose from 1,335 casualties that it reported on Tuesday - 474 civilians killed and 861 injured - since Russia's invasion began on Feb. 24.
Most civilian casualties were caused by explosive weapons including shelling and missile and air strikes, it said on Wednesday. Updated casualty figures from the towns of Volnovakha, Mariupol and Izium were still being corroborated amid allegations of hundreds of civilian casualties, it added.
Russia has denied targeting civilians in its assault on Ukraine.