More than 42 detainees were killed in air strikes on an alleged Islamic State jihadist group prison in eastern Syria, and 15 IS militants also died in the raids, a UK-based monitoring group said on Tuesday.
The strikes took place in the al-Mayadeen area of Syria's Deir Ezzor province and were probably carried out by war planes belonging to the US-led coalition against IS, the Syrian Observatory for Human Rights said.
Jailers were among the IS militants killed in the raid, the Observatory stated on its Arabic website.
The monitor relies for its information on a network of activists and doctors inside Syria.