Srinagar:A car bomb on Thursday killed oil workers and fighters from a US-backed force battling the militant Islamic State group in east Syria, the Kurdish-led alliance said, with a monitor putting the death toll at 20.

A spokesman for the Syrian Democratic Forces (SDF) said the attack killed mostly oil workers, as well as fighters in the village of Shheel close to an oil field acting as a base for the anti-IS force, news agencies reported.

The Britain-based Syrian Observatory for Human Rights said 14 oil workers and six conscripts died after “the car bomb was detonated remotely”.

The SDF fighters were escorting the workers in vehicles from the Omar oil field, the monitor said.

The SDF are fighting to expel extremists from the last shred of their “caliphate” in the village of Baghouz, some 100 km south along the Euphrates river.

The SDF took control of the Omar oil field in October 2017, and have turned it into their main base in the area.

IS seized large swathes of Syria and neighbouring Iraq in 2014, declaring a “caliphate” there, but have since lost all but the Baghouz holdout to various offensives.

US-backed Syrian forces tried on Thursday to negotiate the release of civilians still trapped in the IS group’s last redoubt, as a car bombing killed 20 people near their main base.

The Syrian Democratic Forces (SDF) are working towards evacuating civilians remaining in the holdout in east Syria, so they can retake the last scrap of the dying IS “caliphate” whether through an assault or a surrender deal. (Agencies)