Updated

The U.S.-backed Syrian militia fighting the Islamic State in its last toehold in Syria says there are over 1,000 civilians trapped in the tiny area and that the militant group is preventing them from leaving.

Mustafa Bali, a spokesman for the Kurdish-led Syrian Democratic Forces, tells The Associated Press Sunday that IS has closed all the roads in and out.

SDF officials have said the extremists are hiding among civilians in a tented village and using a network of caves and tunnels. IS, which once ruled a proto-state in large parts of Syria and Iraq, is clinging to an area less than a square kilometer (square mile) in the village of Baghouz, in eastern Syria.

The extremists may include high-level commanders, and could be holding hostages.