rockets and shells, struck southwestern districts, the Observatory said.

JIHADIST GROUPS

Fateh al-Sham played a big part in a rebel attack in July that managed to break the government siege on eastern Aleppo for several weeks before it was reimposed.

Abu Youssef al-Mouhajir, an official from the powerful Ahrar al-Sham Islamist group, said the extent of cooperation between the different rebel factions was unusual, and that the largest axis of attack was on the western edge of the city.

“This long axis disperses the enemy and it provides us with good cover in the sense that the enemy’s attacks are not focused,” he said.

The powerful role played by Jabhat Fateh al-Sham, listed by many countries as a terrorist group, has complicated Western policy towards supporting the anti-Assad opposition.

The United States has preventedmore powerful weapons such as anti-aircraft missiles from being supplied to rebels partly out of fear they could end up in jihadist hands.

The Syrian military source said Friday’s attack had been launched in coordination with Daesh, a group against which all the other rebels, including Fateh al-Sham, have fought.

Daesh fighters did clash with the Syrian army on Friday at a government-held airbase 37km (23 miles) east of Aleppo, next to territory the jihadist group already controls, the Observatory reported.

Syria’s civil war, now in its sixth year, has killed hundreds of thousands of people, displaced half the country’s pre-war population, dragged in regional and global powers and caused a refugee crisis in the Middle East and Europe.

Mouhajir, the Ahrar al-Sham official, said cloudy weather was helping to reduce the