WESTERN-BACKED insurgents unleashed a barrage of shells on government-held districts of Syria’s second city Aleppo yesterday.

In a bid to break their effective encirclement in the ruins of Aleppo, the militants launched an assault on the central Old City district around the medieval Aleppo citadel.

But troops beat back the assault on the bastion, which since 2012 has formed a salient protruding into rebel-held territory.

Some 300 shells fell in the morning alone as the loose alliance of Turkish, Saudi and Qatari-sponsored groups sought to stretch the battle-worn troops to breaking point.

Syria’s official Sana news agency said 13 civilians had been killed and over 150 injured since Sunday night.

To the north of the city, the army and allied forces — possibly including the local Palestinian refugee Jerusalem Brigade — launched its latest attempt to liberate the Handerat refugee camp.

Last week the army overran the Malaa Farms area to the west of Handerat and advanced to within a few hundred yards of the Castello Road, north of Aleppo. The road is the only insurgent supply route into the east of the city, where an estimated 5,000 rebels are dug in.

The south side of the road is held by the Kurdish separatist YPG militia in the Sheikh Maqsoud district, while to the west of there the army is pushing into the Bani Zaid and al-Ayramoun districts, tightening its grip on the city.

Further west, two air strikes destroyed a convoy of tankers apparently smuggling oil or diesel for the insurgents near Termanin.

Al-Jazeera journalist Ibrahim Omar was reportedly killed in the second raid.