Ukraine says two mass burial sites have been found in the recently-recaptured eastern town of Lyman, after Russian retreated.
The Ukrainian governor of the Donetsk region, Pavlo Kyrylenko, said one burial site had about 200 individual graves containing civilian bodies.
The time and cause of death for the deceased is yet to be determined.
Russia withdrew its troops from the strategic town of Lyman, in a significant setback for its campaign in eastern Ukraine.
Lyman is in Donetsk - one of four partially-occupied Ukrainian regions which Moscow declared it was annexing. Ukraine and its Western allies have dismissed the move as an illegal land-grab.