Jan 19 (Reuters) - The Kurdish-led Syrian Democratic Forces said on Monday that forces affiliated with the Syrian government attacked Shaddadi prison in Hasaka in Syria's northeast, where it said thousands of Islamic State militants were being held.
The SDF said it confronted the attackers at Shaddadi and repelled them several times, but that dozens of its fighters had been killed. U.S.-led coalition forces did not intervene despite repeated calls for help, the Kurdish group said.
Earlier, the SDF said it had also clashed with Syrian government forces near the Al-Aqtan prison on the outskirts of Raqqa, another facility holding Islamic State detainees. Raqqa was once the centre of the group's short‑lived "caliphate".
The SDF described the clashes as a "highly dangerous development", warning that any seizure of the prison by government forces "could have serious security repercussions that threaten stability and pave the way for a return to chaos and terrorism".
Syria's ministry of defence denied that government forces attacked the prisons. It said its forces had arrived at Al-Aqtan and had begun "securing" the facility and its surroundings. The army did not enter Shaddadi prison, the ministry said in a statement.
The Syrian army also accused the SDF of being responsible for the release of Islamic State detainees from Shaddadi prison. It said the prison would be handed over to the ministry of interior after a security process.
The SDF said nine of its fighters were killed and 20 wounded in clashes around Al-Aqtan.
Under a sweeping integration deal agreed with Damascus on Sunday, responsibility for prisons housing Islamic State detainees was meant to be transferred to the Syrian government.
After days of fighting with government forces, the SDF - once the main U.S. ally in Syria - agreed on Sunday to withdraw from two Arab-majority provinces it had controlled for years, including oil fields.
Syrian government troops tightened their grip on Monday across swathes of northern and eastern territory abruptly abandoned by the SDF, in a dramatic shift that strengthened President Ahmed al-Sharaa's rule.
In Raqqa, government internal security forces and military police set up checkpoints and checked IDs. Security sources said the city had been cleared of SDF fighters overnight.
(Reporting by Jana Choukeir, Maya Gebeily, Menna Alaa El-Din, Jaidaa Taha and Ahmed Elimam; editing by Alex Richardson, Mark Heinrich and Ros Russell)
