A jail in Syria's Tell Abyad has been emptied of Daesh fighters which Turkish news agency Anadolu reported means Kurdish fighters have set them free.
Security sources told Anadolu the prison, which Turkey had planned to take control of as part of its military campaign in northern Syria, was found empty.
No Daesh fighters were found in the building which had been abandoned with its doors fully open.
Turkish Defence Minister Hulusi Akar said: "We have pictures and videos depicting [Kurdish People's Protection Units] YPG terrorists while evacuating a prison, where ISIS [Daesh] terrorists are detained in northern Syria."
On Wednesday, the Turkish army launched "Operation Peace Spring" in cooperation with the Syrian National Army in the area east of the Euphrates River in northern Syria, to clear it of YPG and Kurdistan Workers' Party (PKK) and Daesh and establish a safe area for Syrian refugees to return to their country.
Though the West has backed the TPG forces in the past, Turkey sees them as an offshoot of the PKK which it designates as a terror group.