Islamic State release hundreds of 'human shields' in Syria

Islamic State group extremists have released hundreds of civilians they used as human shields while fleeing a crumbling stronghold in northern Syria, while the fate of others remained unknown.

The last remaining IS fighters abandoned the city of Manbij near the Turkish border on Friday after a rout the Pentagon said showed the extremists were "on the ropes".

The retreat from the city which IS captured in 2014 was the extremists' worst defeat yet at the hands of the Syrian Democratic Forces (SDF), an Arab-Kurdish alliance backed by US air power.

Fleeing fighters took around 2,000 civilians, including women and children on Friday to ward off airstrikes as they headed towards the IS-held frontier town of Jarabulus, according to the SDF.

At least some captives were later released or escaped, the alliance said on Saturday, but the whereabouts of the rest was unknown.

"There are no more IS fighters" left in Manbij, an SDF member said.

Kurdish television showed footage of jubilant civilians in Manbij, including smiling mothers who had shed their veils and women embracing Kurdish fighters.

One woman burned a black robe that the extremists had forced residents to wear, while men who had lived for weeks under a shaving ban cut their beards.