Fighting between the Syrian army and rebels at a prison in the northern city of Aleppo eased on Thursday, a day after the insurgents assaulted the facility, activists said.
The mostly jihadist rebel forces launched an attack on the regime-controlled prison on Wednesday night, in the heaviest fighting for the jail in months, said the Syrian Observatory for Human Rights.
The military responded to the assault by firing a barrage of shells in the area around the prison.
After midnight, "the intensity of the fighting decreased between the army and members of the Al-Qaeda-linked Al-Nusra Front and another Islamist faction Ahrar al-Sham," it said in a statement.
The Observatory, a Britain-based group that relies on a network of activists and other sources in war-torn Syria for its reports, was unable to say if the army managed to repel the insurgents.
It added that the clashes did not reach the buildings holding thousands of prisoners, mostly common criminals but also Islamist militants.
The jail, located on the northern outskirts of Aleppo, the commercial capital of Syria before a bloody uprising erupted in March 2011, has been besieged by rebels since April.
The Observatory denounced the "alarming" health conditions at the prison, including reported cases of tuberculosis and scabies.