Syria rebels attack barracks in Aleppo

Anti-government Syrian fighters have attacked a military barracks in Aleppo, leaving at least 27 soldiers and 20 rebels dead.

Anti-government Syrian fighters have attacked a military barracks in Aleppo, leaving 50 people dead. (AAP)

Nearly 50 people have been killed after Syrian rebels attacked one of the largest military barracks in the country, in northern Aleppo, the Syrian Observatory for Human Rights said.

It said at least 27 soldiers and pro-regime militiamen were killed and that the rebel losses of 20 dead included a commander.

"Rebels, including fighters from Al-Nusra Front and the Islamic Front, launched an assault today on the barracks in Hanano in Aleppo," Observatory director Rami Abdel Rahman said on Thursday.

State media, meanwhile, reported that the army had "foiled an attempt by terrorist groups to infiltrate the barracks" and killed a number of them.

President Bashar al-Assad's regime refers to rebels battling to topple it as "terrorist" groups.

Abdel Rahman said the barracks is one of the largest in Syria, and is strategically important because of its hill-top outlook on Aleppo.

Once Syria's economic hub, Aleppo has been divided between regime control in the west and rebel control in the east since shortly after combat began there in mid-2012.

Abdel Rahman said the attack began when "rebels detonated explosives in tunnels they had dug beneath army positions around the barracks".