Turkey-backed Syrian rebels on edge of IS bastion al-Bab

Fighters have been less than a kilometre from the Islamic State-held north Syrian town for two weeks, awaiting orders to begin the offensive of the stronhold.

"We drive to the al-Bab frontline every day back and forth. We have been told not to start the offensive to capture the centre of the town. We are on hold," an FSA commander told Turkey's Daily Sabah newspaper.

Having liberated symbolic "doomsday town" of Dabiq from IS last month, FSA fighters have continued their march to al-Bab, some 30km from the Turkish border.

Ankara wants to establish a 5,000-square-kilometre safe zone in Syria, clearing the Manbij area, which serves as an IS supply route from the Turkish border to Raqqa, the de facto capital of the group's so-called caliphate.

Turkey's Operation Euphrates Shield, which launched inside Syria in August. It also aims to clear the border of the Kurdish People's Protection Units (YPG), which it views as a terrorist group, and are aligned with the US-backed Syrian Democratic Forces.

The SDF's presence in the area has angered Ankara which is wary of growing Kurdish autonomy over territories close to Syria's border with Turkey, resulting in frequent clashes between the Kurdish and Turkish forces.