Syrian troops and their allies, backed by Russian jets, attacked insurgent fighters south of Aleppo on Friday, a source in Syria and a monitoring group said, as the army expands a counter-offensive with support from Moscow's two-week-old air campaign.
"The military operation has started in rural southern Aleppo," a pro-government source in Syria said.
Rami Abdulrahman, director of the Syrian Observatory for Human Rights, said there were heavy clashes near the Jebel Azzan region, about 12 km (8 miles) south of Aleppo city, control of which is divided between government forces and rebels.
The area the army and Russian jets were targeting was close to a main road heading south towards the capital Damascus, Abdulrahman said.
Since Russia launched air strikes on September 30 in support of President Bashar al-Assad, the army has waged offensives against insurgent-held regions in western Syria, including a rebel pocket north of Homs and areas of Hama, Idlib and Latakia provinces taken by the rebels over the summer.
Beirut-based al-Mayadeen television said on Friday the army was fighting on three fronts south of Aleppo.
Abdulrahman said the army had recaptured the village of Abtin from rebel fighters, as well as a tank battalion base close to the village of Sabiqiya. Both villages lie close to Jebel Azzan. Rebels had hit one army tank with a US-made TOW anti-tank missile.
He said Syrian troops were being supported by allied militia forces and Iranian fighters.
The involvement of Iranian soldiers could not immediately be confirmed, but two senior regional sources told Reuters this week that Iran has sent thousands of troops to Syria in recent days to bolster the offensive underway in Hama province and in preparation for another in the Aleppo area, which is in northern Syria.
The Observatory said the death toll from Thursday's fighting and air strikes north of Homs had risen to 60, including 30 women and children.
