The latest satellite images appear to show around 200 mass graves - dug close to the besieged Ukrainian city of Mariupol.
But local officials say as many as 9,000 people could be buried there.
The Kremlin’s always denied harming civilians.
Meanwhile the US is sending hundreds of millions of- euro of military equipment to Ukraine, but former UK defence Minister Tobias Ellwood thinks the west needs to go further:
"Are we content with seeing part of Donbass remain in Russians hands? Or are we going to go back to pre-2014 borders and push Russia out? Which is where I would like to go. Otherwise Putin will simply do all this again because he'll survive and then they'll attack another country in a couple of years time".
