The SDF said clashes were continuing around al-Aqtan prison in Raqqa, with nine of its fighters killed and 20 others injured.

In a statement, the SDF claimed its forces had been coordinating with a US-led international coalition for the past three days to transfer ISIL detainees held at the prison to “safe locations”.

However, the group said that despite “repeated promises”, the coalition had so far taken “no practical steps” to carry out the transfers.

The SDF added that its forces had continued efforts to protect the prison during clashes with what it described as “Damascus-affiliated factions” that it said were attacking the facility.