Syria's Interior Ministry said on Friday it had taken over al-Aqtan prison in the city of Raqqa in northeastern Syria, a facility that was formerly under the control of Kurdish-led Syrian Democratic Forces (SDF).
The prison has been holding detainees linked to the ISIS group, and witnessed clashes in Its vicinity this week between advancing Syrian government forces and the SDF.
It was not immediately clear how many ISIS detainees remain in al-Aqtan prison as the US military has started transferring up to 7,000 prisoners linked to the extremist group from Syrian jails to neighboring Iraq. US officials say the detainees are citizens of many countries, including in Europe.
"Specialized teams were formed from the counter-terrorism department and other relevant authorities to take over the tasks of guarding and securing the prison and controlling the security situation inside it," the Interior Ministry said in a statement.
Under a sweeping integration deal agreed on Sunday, responsibility for prisons housing ISIS detainees was meant to be transferred to the Syrian government.
The SDF said on Monday it was battling Syrian government forces near al-Aqtan and that the seizure of the prison by the government forces "could have serious security repercussions that threaten stability and pave the way for a return to chaos and terrorism".
The US transfer of ISIS prisoners follows the rapid collapse of Kurdish-led forces in northeast Syria. Concerns over prison security intensified after the escape on Tuesday of roughly 200 low-level ISIS fighters from Syria's Shaddadi prison. Syrian government forces later recaptured many of them.