BEIRUT: Syrian government forces backed by Russian airpower and allied militias opened a new front against militants south of second city Aleppo on Friday.

The fresh offensive came as Turkey said it had downed an drone of unknown origin that violated its air space close to the Syrian border.

The Aleppo offensive is the fourth that President Bashar al-Assad's regime has launched since Moscow began an air campaign on September 30.

Aleppo city has been divided between regime control in the west and militant control in the east since mid-2012.

The situation is largely reversed in the countryside surrounding the city, which was once the country's economic hub, and the front lines have been static for some time.

A security source said the operation in southern Aleppo province was backed by Russian strikes and fighters from Iran and Lebanon's Hezbollah militia.

The joint command for the Aleppo operation issued a statement saying the army had begun operations on the western and southern outskirts of Aleppo “to liberate you from the armed terrorist groups.“

'Dozens' of Russian strikes

The Britain-based Syrian Observatory for Human Rights said the regime had taken control of two villages during the offensive so far, and that Russian warplanes were pounding two others.

Observatory head Rami Abdel Rahman said Russia had carried out “dozens” of strikes on the area, which is controlled by a patchwork of militant groups, including Jihadists and Al-Qaeda affiliate Al-Nusra Front.

The Aleppo fighting comes a day after regime forces began an operation north of the city of Homs, which lies in the centre of the country and is largely under government control.

Syrian state media said the operation was intended to restore “safety and security” to the area and would not target civilians.

Since Syrian forces began ground operations in tandem with Russian air strikes on October 7, their focus has appeared to be a stretch of highway between Aleppo and Homs.

The fighting north of Homs on Thursday centred around the town of Talbisseh on the highway, and regime operations in neighbouring Hama province have also focused on the key road.

Syrian forces have also sought to reinforce the coastal province of Latakia, a regime stronghold, fighting militants in the north of the province.

Moscow says its strikes have targeted the self-styled Islamic State (IS) group and other “terrorists.“

It said on Friday that it had hit more than 380 IS targets in Syria since the start of its bombing campaign.