Ukrainian President Volodymyr Zelenskyy on Monday said the legal basis is being put in place to bring "culpable Russian troops" to justice over alleged atrocities.
Moscow is facing global revulsion and accusations of war crimes after the Russian pullout from the outskirts of Kyiv revealed streets strewn with corpses of what appeared to be civilians, some of whom had seemingly been killed at close range.
The grisly images of battered bodies left out in the open or hastily buried led to calls for tougher sanctions against the Kremlin, namely a cutoff of fuel imports from Russia.
Speaking in a recorded message Zelenskyy accused Russia of "trying to distort facts", and having "launched a campaign of fakes to hide their guilt of mass killing of civilians in Mariupol".
"They are making dozens of staged interviews, edited recordings. They will deliberately kill people in a way to make it look like as if they were killed by someone else. Probably, occupiers will now try to hide traces of their crimes. They didn't make it in Bucha when they were withdrawing, but it might be possible at other territories," he said.
During the message the Ukrainian president said "some European leaders" had waited until "hundreds of our people" had died "in agony" to bring on more international pressure on Russia.
Germany and France reacted by expelling dozens of Russian diplomats, suggesting they were spies, and U.S. President Joe Biden said Russian leader Vladimir Putin should be tried for war crimes.
ALSO WATCH: Scenes of horror from Ukraine's Bucha as Russian troops withdraw from city