Beirut, Lebanon: Hundreds of civilians used by the Islamic State group jihadists as human shields while retreating in northern Syria were rescued, US-backed forces and a monitor said Saturday.

A source from the Syrian Democratic Forces, which pushed IS out of the city of Manbij this week with the aid of US-led air strikes, told AFP that some of the civilians were able to escape while ‘others were freed’. 

The Syrian Observatory for Human Rights, a British-based monitor, said that several hundred of the civilians taken were no longer held by IS.

The SDF, an Arab-Kurdish alliance, launched an assault in May on Manbij, on a key jihadist supply route between the Turkish border and IS's de facto Syrian capital Raqa.

IS fighters seized around 2,000 civilians as they fled Manbij on Friday, using them as protection against air strikes en route to the jihadist-held town of Jarabulus, on the Turkish-Syrian border.

‘Among the civilians taken by IS there were people used as human shields but also many who chose voluntarily to leave the town due to fear of reprisals’ by the SDF, Observatory head Rami Abdel Rahman said.

The jihadists, who have suffered a string of losses in Syria and Iraq, have often staged mass abductions when they come under pressure to relinquish territory they hold.

IS has also booby-trapped cars and carried out suicide bombings to slow advances by their opponents.

According to the Observatory, 437 civilians, including more than 100 children, were killed in the battle for Manbij and surrounding territory.

Around 300 SDF fighters died, along with more than 1,000 jihadists, it said.