Ukraine’s president has described the bombardment of Kharkiv, which killed dozens of civilians, as a war crime.
Volodymyr Zelensky said there were eyewitness accounts of civilians being deliberately targeted during Monday’s attack on Ukraine’s second largest city.
Rights groups also said war crimes may have occurred during Russia’s invasion.
The International Criminal Court’s (ICC) is looking to launch its own investigation into the allegations.
Chief prosecutor Karim Khan said there is “reasonable basis” to believe war crimes or crimes against humanity have been committed in Ukraine.
Days after launching its invasion, Russia is attacking Ukraine on several fronts, but its advance has been slowed by Ukrainian resistance.
