AMSTERDAM - Prosecutors for International Mobile Justice teams are investigating as possible war crimes the ongoing Russian missile strikes in Kyiv and cities across Ukraine that have so far killed at least 26 people, an official told Reuters on Wednesday.

Monday's attacks killed 19 people, wounded more than 100 and knocked out power across the country in Moscow's biggest aerial offensive since the start of its invasion on Feb 24.

Another series of strikes on Tuesday killed seven people in the southeastern town of Zaporizhzhia and left part of the western city of Lviv without power.

War crimes investigators visited sites in the capital and examined damage to civilians and civilian infrastructure, said British attorney Nigel Povoas, lead prosecutor for the International Mobile Justice teams, which is assisting Ukrainian investigations.

"We visited all the sites in Kyiv yesterday," Mr Povoas told Reuters.

"Even the claimed widespread attacks on energy and communications infrastructure appear to have minimal impact on military operations and maximum impact on the health, suffering and spread of terror within the civilian population with winter approaching."

Russia denies targeting civilians in its military operation in Ukraine. REUTERS