Updated

A spokesman for the U.S.-led coalition battling the Islamic State group says an estimated 4,000 civilians are still trapped in the Syrian city of Raqqa, once the extremists' de facto capital, and that coalition allies are working out ways to evacuate them.

Col. Ryan Dillon says the Raqqa Civil Council, a local administration of Arab and Kurdish officials, is leading the discussions. It's not clear with whom the council is speaking inside Raqqa.

Dillon said on Wednesday that the coalition wouldn't accept a negotiated surrender of up to 400 militants believed holed up in the last part of the city that remains in IS hands.

Dillon says up to 15 militants have surrendered in the past three weeks in Raqqa. The battle for the city is in its final stages.