A US satellite firm says it has identified a mass burial site containing about 200 graves near Mariupol, a city Russian forces have been trying to wrest control of for weeks.
Maxar said its images showed an expansion of graves that began at the end of March.
Local Ukrainian officials accuse the Russians of burying Mariupol civilians killed by Russian troops there.
Moscow has not yet responded.
Russian troops control most of Mariupol after weeks of bombardment and fighting, but some Ukrainian forces remain in a sprawling steelworks in the city. President Putin has abandoned plans to storm the Azovstal plant and instead told troops to seal it off.
The alleged mass grave is near a village called Manhush about 20km (12 miles) west of Mariupol. Maxar said there were four sections of linear rows about 85m long.
The BBC has not independently verified the images.
BBC
