ISIS have killed more than 700 members of a tribe in eastern Syria in two weeks mostly civilians, the Syrian Observatory for Human Rights said on Saturday.
The monitoring group said that were 100 fighters among the members of the Shaitat tribe who were killed in several villages in the mainly ISIS-controlled eastern province of Deir Ezzor.
The head of Observatory which relies on a vast network of activists and medics on the ground said that the fate of 1,800 other members of the tribe was unknown.
On August 5, the Observatory said IS beheaded three Shaitat tribesmen and put their heads on public display.
Also Saturday details emerged of a "massacre" carried out by ISIS in a northern Iraq village.
Dozens of civilians were killed, most of them followers of the Yazidi faith, Kurdish officials said.
Militants entered the village of Kocho on Friday and "committed a massacre," senior Iraqi official Hoshyar Zebari told AFP, citing sources from the region and intelligence reports.