Canadian Prime Minister Justin Trudeau said on Sunday that the mass graves found in Ukraine are evidence of war crimes committed by Russia, and that there is a need for full accountability for its actions.

Trudeau, who is in London to attend the funeral of Queen Elizabeth II, told reporters that he met with British Prime Minister Liz Truss and that the Russian invasion of Ukraine was at the top of their agenda, adding: "It is clear that the UK and Canada have been among the strongest countries in standing to support Ukraine and respond to Russia's illegal actions."

Trudeau also said that these actions "increasingly include clear war crimes, including utterly unacceptable crimes, whether we think about what was found in Bucha or the discovery of mass graves in territory regained by Ukraine."

Ukrainian officials said last week that they found 440 bodies in forests near Izyum in northeast Ukraine, a town that Ukrainian forces have regained control of, saying most of the dead were civilians and causes of death were not determined. The Kremlin has not commented on the discovery of the graves, but Moscow has repeatedly denied deliberately attacking civilians or committing atrocities. Trudeau said, "There must be a proper investigation and transparency, and Vladimir Putin and his supporters and the Russian military must be held accountable for the atrocities they have committed and continue to commit in Ukraine."

Trudeau, who was scheduled to meet with Ukrainian Prime Minister Denys Shmyhal on Sunday evening, expressed that Canada strongly supports Ukraine and will continue to provide assistance, and that his talks with Truss also touched on trade relations between their two countries. Canada and the UK discussed the trade deal being negotiated, which is "progressing well," as well as Canada's support for Britain's potential accession to the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP).