“We have got increasing information on mass graves that are there,” Matilda Bogner told journalists by video link from Ukraine, saying some of the evidence came from satellite images.
The U.N. rights office, which has some 50 staff in the country, has so far counted 1,035 civilian deaths since Russia invaded on Feb. 24.
But verification difficulties meant that toll included “very few” from Mariupol, which has been under heavy bombardment for weeks, Bogner said.
“The extent of civilian casualties and the destruction of civilian objects strongly suggests that the principles of distinction, of proportionality, the rule on feasible precautions and the prohibition of indiscriminate attacks have been violated,” she said.
A Reuters journalist who reached a part of Mariupol held by Russian forces on Sunday saw several bodies lying by the road and a group of men digging graves in a patch of grass by the roadside.
Bogner’s team is probing alleged human rights violations, such as reports that Russian forces had shot and killed civilians in their cars as they were fleeing; dozens of cases of disappearances of Ukrainian officials and journalists; and the forced movement of civilians into Russian-held territory.
Russia, which has called its actions since Feb. 24 a “special operation”, has denied targeting civilians in Ukraine. Russian news agencies have said buses have carried several hundred people Moscow calls “refugees” from Mariupol to Russia.
Bogdan said her team have also received reports of violations by Ukrainian forces including indiscriminate shelling in Donetsk, eastern Ukraine, and two alleged killings of civilians due to their perceived support for Russia.
Ukrainian authorities have repeatedly said that they have never targeted civilians, adding that the people who are in Donetsk and Luhansk are Ukrainians.
