At least 57 people have been killed in a suspected U.S.-led coalition air strike on a prison run by the extremist group Islamic State (IS) in eastern Syria, activists say.
The Britain-based Syrian Observatory for Human Rights said 42 prisoners and 15 IS militants died when the facility near Al-Mayadeen in Deir al-Zour Province was hit on June 26.
Strikes were conducted on "known ISIS command-and-control facilities and other ISIS infrastructure" in the area on June 25-26, coalition spokesman Colonel Joe Scrocca said on June 27, using an alternative name for the IS group.
"This mission was meticulously planned and executed to reduce the risk of collateral damage and potential harm to noncombatants," he also said, adding that the coalition was looking into the casualty reports.
Al-Mayadeen, which lies about 45 kilometers southeast of the city of Deir al-Zour, has been targeted frequently by coalition aircraft.
