TWO FACTIONS in the Western-backed Syrian insurgency were fighting on opposite sides yesterday as Damascus militants helped the government army defeat an Islamic State (Isis) offensive.

Al Masdar News reported that army forces allowed a contingent of Army of Islam guerillas to travel from their stronghold in Ghouta, east of the capital, to Al-Dumayr, in the east of the province, where other members of the same group are fighting Isis.

And yesterday morning Syrian air force jets blitzed Isis units attacking Army of Islam positions in Jabal Ruhaybeh, helping their erstwhile enemies repel the assault.

Isis has launched an offensive in the east of Damascus province in recent days, seizing an army base but failing to capture the Tishreen power plant and the al-Dumayr air base.

But Syria’s official Sana news agency said yesterday that Isis had kidnapped some 300 workers from the nearby al-Badia Cement Company factory.

Military sources said more than 70 Isis terrorists had been killed in the area in the previous two days.

The Army of Islam is part of the Saudi-convened, Washington-backed High Negotiations Committee (HNC) of supposedly moderate insurgent groups at the adjourned UN peace talks in Geneva.

The HNC is dominated by the Army of Islam and Ahrar ash-Sham, itself in alliance with the al-Qaida-affiliated Nusra Front in Idlib and Aleppo under the banner of the Army of Conquest.

That alliance broke the Russian-US brokered ceasefire last weekend when it launched a major offensive towards Aleppo.

Air force planes dropped thousands of leaflets on Jisr al-Shughour yesterday urging militants to “surrender now or leave,” indicating an imminent offensive to liberate the town, the gateway to Idlib.

The government offensive comes after the army and allied militias drove Isis from the ancient city of Palmyra and then Quryatayn to the west.

Those victories have opened the way to lifting the Isis siege of the eastern city of Deir Ezzor and striking at the terror group’s de facto capital Raqqa.

On Wednesday, the Russian ceasefire monitoring centre in Latakia said that some 1,500 Nusra Front terrorists with three captured army tanks had attacked the Aleppo suburb of Sheikh Maqsoud, killing 29 civilians.

Sheik Maqsoud, held by the Kurdish YPG militia, has repeatedly been targeted by shelling from Nusra Front and Free Syrian Army forces occupying the east of Aleppo and countryside to the north.

Last month, extremists fired toxic and incendiary white phosphorus rounds into the district.