More than 150 Syrian soldiers were stripped and marched into the desert to be shot by Islamic State militants, activists have claimed.
A video has been posted to YouTube purporting to show the men, who are barefoot and in their underwear, being escorted into the desert.
It then goes black before revealing a similar number of men, also in their underwear, lying dead in the sand.
The video has yet to be verified but correspond to other reports from the region, and tie up with a statement and claims made via Twitter relating to the mass killing of troops captured in recent fighting for a string of military bases in north-eastern Syria.
There has been no immediate comment from the Syrian government.
More top news
Choir wins public vote, while judges pick dancers ahead of 12-year-old singer-songwriter Henry Gallagher.
The hunt for murder suspect Jed Allen has ended after police found his body two days after discovering his mother, stepdad and sister dead.
A woman who had been searching for her mother for more than 10 years has been reunited with her after posting an appeal on social media.