The Observatory said more than 50 troops were summarily executed, 19 more were killed in a double suicide attack and at least 16 others had died in the IS assault launched early Thursday.

„Hundreds of troops surviving withdrew on Friday to safe places — either to nearby villages whose residents oppose IS or to nearby Brigade 93 — but the fate of some 200 remains unknown,“ said Abdel Rahman.

„Some of the executed troops were beheaded, and their bodies and severed heads put on display in Raqa city,“ stronghold of the feared IS, he said.