Damascus: Syrian authorities have freed for “humanitarian reasons” 366 detainees from Aleppo prison in the north of the country, which is under rebel siege, state news agency Sana reported on Friday.

The Syrian Observatory for Human Rights said a first group of 10 prisoners were freed on Thursday and that more would follow, adding that most of the prisoners were convicted criminals.

Al Qaida-affiliated Al Nusra Front and other Islamist rebel groups fighting to topple President Bashar Al Assad have laid siege to the prison for the past eight months.

“The authorities have released 366 detainees from Aleppo’s central prison...for humanitarian reasons due to the siege imposed by terrorists,” Sana said, referring to the rebels.

Observatory chief Rami Abdul Rahman told AFP by telephone from Britain that conditions inside the prison are “horrific” and prisoners are being freed due to outbreaks of disease, including tuberculosis.

“The evacuation of prisoners began yesterday and the Red Crescent has successfully brought out 10 people. Others will gradually be set free,” he said.

The Observatory said the Red Crescent was also taking in food rations, medicine and clothes into the prison on the outskirts of Aleppo, Syria’s second city and former commercial hub.

More than 3,000 prisoners are held in the jail, including Islamists, activists and minors.

Rebels have tried to storm the prison on several occasions but loyalist troops have repelled them, although fighting continues to be reported in the vicinity of the jail.

Tens of thousands of people have been detained in Syria over the course of an uprising that broke out in March 2011. Torture is systematic in Syria’s jails, rights groups say.