Syrian Democratic Forces say they are battling government forces around a prison holding fighters from the armed group ISIL near Raqqa in the northeast, APA reports.
State news agency SANA reports at least three soldiers have been killed.
The army is currently clashing with Kurdish forces and Bashar al-Assad “regime remnants” seeking to derail the ceasefire signed on Sunday, it said.
The fighting is the first reported since the truce was agreed between the government and Syrian Democratic Forces (SDF).