(Adds Pentagon official's comment, paragraphs 13-15)
DEIR AL-ZOR PROVINCE, Syria, March 8 (Reuters) - U.S-backed fighters will resume their assault on Islamic State's last, small patch of ground in eastern Syria if no more civilians come out by Saturday afternoon, one of their spokesmen said on Friday.
The Syrian Democratic Forces (SDF) have slowed their offensive on the jihadist enclave at Baghouz near the Iraqi border to allow many thousands of people to leave over the past few weeks.
A month ago the SDF launched what it called a "final battle" to take the cluster of houses and farmland, and people leaving the enclave have described harrowing conditions of peril and hardship.
The SDF said a week ago that it believed all civilians had come out and renewed its assault, leading to a new surge of displacement, including obdurate disciples of Islamic State, some of its captives and hundreds of surrendering fighters.
A Yazidi woman who emerged on Thursday spoke of years of enslavement and abuse by the jihadists. Two Iraqi boys who came out with her, pretending to be her brothers, said many fighters remained dug into tunnels in Baghouz.
However, the head of the SDF media centre, Mustafa Bali, said no more people had emerged on Friday.
"We are waiting for tomorrow morning or perhaps until the afternoon, we'll give another space, for the possibility that civilians are present and the chance to get them out," he said.
After that, "if no civilian or terrorist comes out, we will launch our military operation anew."
The capture of Baghouz will mark the end of Islamic State's territorial rule over populated areas of Iraq and Syria, and the culmination of a U.S.-backed military campaign waged by the SDF for four years.
After suddenly seizing swathes of land straddling the Iraqi-Syrian border in 2014 and declaring it their caliphate, Islamic State was beaten back by numerous local and foreign forces in both countries, suffering major defeats in 2017.
However, the jihadists remain a menace. In Iraq they have gone to ground, staging waves of killings and kidnappings. In Syria, their comrades hold out in remote desert areas and have carried out bombings in areas controlled by the SDF.
Those who have fled Baghouz have mostly gone to al-Hol, a displacement camp in northeast Syria whose population has swelled to 62,000 people, 90 percent of them women and children.
A senior U.S. defence official in Washington said it could take a couple of days to retake Baghouz, or even weeks. About 20,000 Islamic State fighters and family members have come out of Baghouz so far, said the official, who requested anonymity.
"We have been consistently wrong, as have our SDF partners, on how big this is in terms of both fighters coming out and also what we consider ISIS affiliates, these are women and children," the official said.
SDF forces were holding about 4,000 suspected Islamic State fighters from Iraq and Syria and more than 1,000 foreign fighters, the official said.
(Reporting by Rodi Said in Deir al-Zor province, Syria; Additional reporting by Idrees Ali in Washington; Writing by Lisa Barrington and Angus McDowall; Editing by Peter Graff/Mark Heinrich and Grant McCool)
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