Ukraine’s President Volodymyr Zelensky has said peace talks will continue with Russia despite accusing Moscow of war crimes and genocide.
Mr Zelensky was speaking in Bucha, near the capital Kyiv, where bodies of civilians were found strewn on the streets after Russian troops withdrew.
Ukraine says bodies of 410 civilians have been found in areas around Kyiv.
Russia, without evidence, says photos and videos of atrocities are “a staged performance” by Ukraine.
Mr Zelensky said Russian troops “treat people worse than animals. That is real genocide, what you have seen here”.
Responding to a question from the BBC on whether it was still possible to talk peace with Russia, Mr Zelensky said: “Yes, because Ukraine must have peace. We are in Europe in the 21st Century. We will continue efforts diplomatically and militarily.”
Ukraine has started a war crimes investigation after bodies of civilians were found in Bucha and Irpin, near Kyiv.
In Bucha, witnesses described Russian soldiers firing on men fleeing after refusing to allow them to leave through humanitarian corridors.
At least 20 dead men were found lying in the street. Many had extensive wounds – some had been shot through the temple, as if executed. Some had clearly been run over by tanks.
Satellite images taken by Maxar show a 14m (45ft) mass grave in Bucha near the church of St Andrew and Pyervozvannoho All Saints.
In the nearby village of Motyzhyn, a BBC team were taken to see a shallow grave – four bodies were visible, and Ukrainian officials said there could be more.
Three of the bodies have been identified as that of the head of the village, Olha Sukhenko, her husband and her son. The fourth has not been identified yet. It is unclear when they were killed.
In Irpin, there is evidence of people being shot at as they tried to flee the commuter town.
On 6 March four civilians – a woman, her teenage son, her daughter of around eight years of age, and a family friend – were all killed by mortar fire as they tried to cross a battered bridge.
Russian Foreign Minister Sergei Lavrov has described the alleged atrocities in Bucha as an “act” that was “staged” several days after Russian forces withdrew, according to Tass news agency.
“We categorically reject all allegations,” Kremlin spokesman Dmitry Peskov told journalists.