BEIRUT: Fresh fighting erupted Tuesday in Syria's second city Aleppo, where the army shelled several rebel-held areas, a rights watchdog said, after a bloody day in which 160 people were killed nationwide.

“Fighting broke out between government forces and rebel fighters in the (southwestern) districts of Saif al-Dawla and Salaheddin alongside explosions in the area,” the Syrian Observatory for Human Rights said.

Salaheddin is controlled by regime forces, although there are pockets of rebel fighters, according to the Britain-based watchdog.

A civilian was shot dead by a sniper in Saif al-Dawla, the second rebel stronghold in the northern city, where the army advanced Monday with the help of tanks and armoured vehicles.

Government forces also pounded the rebel-held eastern districts of Sakhur, Hanano and Shaar, the Observatory said.

In the capital Damascus, residents fled the central neighbourhood of Qaboon, fearing a major military onslaught, as security forces raided the districts of Midan in the south and Shaghur in the centre.

Government forces had launched a major sweep of the capital on Monday, including the historic Old City, arresting at least 22 people, according to the Observatory.

Outside the city, government forces shelled the suburbs of Qudsaya and Daraya, while elsewhere in the province of Damascus, a civilian and a defected soldier were killed in the town of Al-Tal.

The opposition Syrian National Council called attention to the situation in Al-Tal, describing it as a “disaster area” after five days of army shelling.

The Council urged “all capable citizens to come to the aid of the town with any means possible and to break the siege of the criminal regime by providing food and medical aid to the people.”

Elsewhere, a woman was shot dead by a sniper in the southern province of Daraa, bringing Tuesday's initial toll to four people killed.

On Monday, 100 civilians, 19 rebels and 41 soldiers were killed across Syria, according to the watchdog. Among the casualties were 60 people killed in Damascus province alone, including 57 civilians.