At least 13 people, including nine children, were killed in air strikes on the opposition-held east of Aleppo on Friday (August 5th), the Syrian Observatory for Human Rights said.

The latest civilian deaths come as opposition fighters, including some extremist factions, press an assault intended to break a regime siege that began July 17th.

In an audio message released Friday, Abu Mohamed al-Joulani, the head of al-Qaeda's former affiliate in Syria, pledged the operation would soon succeed.

The assault started Sunday and is targeting the Ramussa district that contains the main supply route to the regime-held west of the city.

After some initial advances, regime forces have pushed back opposition fighters, which include extremists from al-Joulani's faction, now known as Jabhat Fateh al-Sham.

According to the Observatory, at least 112 civilians, including 33 children, have been killed in Aleppo by both sides since the opposition assault began on Sunday.

Elsewhere in Aleppo province, the Observatory said, an Arab-Kurd alliance is advancing inside the "Islamic State of Iraq and the Levant" (ISIL) stronghold of Manbij.

Observatory chief Rami Abdul Rahman said the Syrian Democratic Forces (SDF) now hold 70% of the town.

"ISIL has entered its final phase in the town of Manbij," he told AFP, adding that ISIL is keeping a number of civilians there as human shields.