President Volodymyr Zelensky accused Russia on Friday of torture and war crimes in Ukraine's northeast and likened the aftermath in the recaptured areas to Russia's withdrawal from near Kyiv months ago.
In an interview at his presidential office, he told Reuters that many Ukrainians were buried at sites in the northeast including whole families and people who were tortured.
"As of today, there are 450 dead people, buried. But there are others, separate burials of many people. Tortured people. Entire families in certain territories," he said.
Asked if there was evidence of war crimes, he said: "All this is there. Investigative commissions with international partners, joint investigative commissions," he said.
"There is some evidence, and assessments are being conducted, Ukrainian and international, and this is very important for us, for the world to recognise this," he said.
The Kremlin did not immediately respond to a request for comment on Zelensky's allegations.
Russia regularly denies targeting civilians during what it calls its "special military operation" in Ukraine and has said in the past that accusations of human rights abuses are a smear campaign.
The governor of Kharkiv region, Oleh Synhubov, told reporters on Friday at one of the burial sites in the city of Izium that some bodies exhumed there had been found with their hands tied behind their backs.
Moscow has not commented on the mass burial site in Izium, which was a Russian frontline stronghold before Ukraine's counter-offensive forced its forces to flee.
NO EARLY END TO WAR
Zelensky, who visited Izium earlier this week, also reiterated during Friday's interview his appeal for foreign powers to step up weapons supplies to Ukraine, saying the outcome of the war hinged on their swift delivery.
He lauded Ukraine's rapid counter-offensive but said it was too soon to talk of the tide turning in a war now well into its seventh month.
"It's early to talk about an end to this war. I think it’s early," he said.
Speaking in Samarkand, Uzbekistan, on Friday, Russian President Vladimir Putin said he had sent his armed forces into Ukraine on Feb 24 as part of efforts to prevent what he said were Western efforts to "break up" Russia. He signalled that military operations in Ukraine would continue.