13,000 Syrian residents flee Manbij amid anti-IS offensive

"The fleeing increased after the Syrian Democratic Force [SDF] besieged Manbij" on June 10, Rami Abdel Rahman, head of the Syrian Observatory for Human Rights monitoring group said, adding that on Sunday "hundreds of people fled a southern district of the town where there have been fierce clashes in recent days".

In June, the UN’s humanitarian office said 60,000 civilians were still in the town but has not yet released an updated figure.

Some residents attempting to escape the SDF-controlled district were killed by IS snipers while fleeing towards the southern territories, Abdel Rahman said.

But the operation, which began more than one month ago has made little progress in recent days due to the release of suicide attackers dispatched to resist the SDF offensive.

"Daesh has used car bombs against a number of our positions," an SDF field commander told AFP on condition of anonymity.

The US-backed Kurdish-Arab alliance seized a key road junction and grain silos overlooking the city last week, pushed further into the Islamic State group stronghold.

The city lies close to the border with Turkey and is a key staging post on the extremists' supply line to areas under its control in eastern Syria and neighbouring Iraq.

The Observatory said IS and the SDF were locked in intense street fighting as the extremists tried to defend their positions.

The militants took an estimated 900 Kurdish civilians hostage in areas under their control west of the city, according to the Observatory and Kurdish officials.

Manbij lies in the eastern plains of Aleppo province, which has become a battleground between an array of competing armed groups, including al-Qaeda, rebels and government forces, as well as the SDF and the IS group.