Islamic State fighters in the Syrian city of Raqqa are expected to fight to the death, but some local militants have surrendered recently as US-backed forces close in on their last strongholds, a US coalition spokesman said on Wednesday.Colonel Ryan Dillon said officials in the Raqqa Civil Council, which is to govern the city after IS has been driven out, were working to negotiate the safe passage of thousands of civilians being held hostage.But the coalition would not support any negotiated withdrawal of fighters, he said."The coalition would not be party to a negotiated settlement. (But) we're jumping ahead of anything that's being discussed right now ... as (the council) try to get civilians out," he told Reuters by phone.Up to 400 militants are believed to remain in a small part of Raqqa surrounded by the Syrian Democratic Forces (SDF) alliance of Kurdish and Arab militias, he said."The foreign fighters (in IS), we fully expect them to fight till the end - there's a hardcore of (foreign) fighters."But we have seen a rate of four to five ISIS fighters surrendering a week, including emirs - local leaders within Raqqa - over the past month," Dillon said, using another acronym for Islamic State.The SDF said on Sunday it expected Raqqa's capture to be announced within days.Islamic State took over the city in 2014 as it seized swathes of Syria and Iraq. Raqqa served as the group's de facto Syrian capital, from where Islamic State plotted deadly attacks abroad.