The offensive on the last enclave held by the Islamic State group in eastern Syria has been blunted by the discovery of hundreds of civilians still living there, a commander with the Kurdish-led force fighting the extremists said.
The US-backed force known as the Syrian Democratic Forces (SDF) launched the offensive to liberate the IS-held village of Baghouz a week ago, after more than 20,000 civilians, many of them foreign wives of IS militants, were evacuated through a corridor from the area in the eastern province of Deir el-Zour.
Adnan Afrin told the Associated Press that in the last three days, IS militants had brought hundreds of civilians up from underground tunnels to make the SDF and the US-led coalition aware of their presence.
Kurdish-led forces closed in on the Syrian border town of Baghouz, where Islamic State fighters were putting up a desperate fight defending the last shred of the original "caliphate" https://t.co/Lfnp8fv11m pic.twitter.com/2GtuIq4JP0— AFP news agency (@AFP) February 14, 2019
He estimated that around 1,000 civilians, including women and children, were still in the area. He added that militants were hiding among them and using them as human shields.
"This was a surprise. We did not imagine there would be this number of civilians left," Mr Afrin said.
He said they were likely to be families of IS militants, but their discovery has blunted the offensive. "We do not want to cause a massacre against civilians in the last (IS) pocket," he said.
A blitz of air strikes and shelling last week was believed to signal the end of the campaign against IS in its last toehold in Syria.
Thousands of people, including many foreign fighters and their families, emerged from the area amid ferocious fighting as the SDF closed in from three sides under the cover of air strikes by the US-led coalition.
IS militants are clinging to their last patch of land in Baghouz, and the anticipated declaration of victory against the group has been delayed by the discovery of civilians.
Organised access to the front line has been restricted for journalists amid security concerns, particularly after the injury of an Italian photographer earlier this week.
US-backed forces are conducting precision operations targeting the militants' outposts in and around the village of Baghouz and working to clear surrounding villages of remaining fighters, SDF officials said.
The capture of Baghouz and nearby areas would mark the conclusion of a devastating four-year global campaign to end the extremist group's hold on territory in Syria and Iraq, their so-called "caliphate", which at the height of IS power in 2014 covered nearly a third of Iraq and Syria.
President Donald Trump has said the group is all but defeated. He announced in December that he would withdraw the 2,000 American troops in Syria.
It is not clear whether IS is holding any civilian prisoners in the enclave beyond their own families.
"We aim to save any prisoners, but we have no information about them. They can be among the civilians, or in underground prisons, we have no information," said Mr Afrin.
Meanwhile, the Pentagon's leading official said he foresees a "bigger and stronger" American-led international coalition combating IS globally as the US withdraws its troops.
Pat Shanahan, on his first trip abroad as the acting secretary of defence, made his comment after meeting representatives of the dozen or so countries that provide troops in Iraq and Syria.
"While the time for US troops on the ground in north-east Syria winds down, the United States remains committed to our coalition's cause, the permanent defeat of Isis, both in the Middle East and beyond," Mr Shanahan said.
Mr Trump's decision in December to pull out of Syria angered some allies, confounded US military officials and prompted Jim Mattis to resign as defence secretary.
General Joseph Votel, who as head of US Central Command is overseeing military operations against IS in Syria and Iraq, said last week that he was not consulted before Mr Trump made his decision.
In an interview with CNN on Friday, Gen Votel went a step further, saying: "It would not have been my military advice at that particular time. I would not have made that suggestion, frankly."
Mr Shanahan said the US will "continue to support our local partners' ability to stand up to the remnants of Isis", but did not explain how.
He said that in Syria, IS has lost most of its leadership and resources - although he did not say it has lost all its territory.
"Together, we have eliminated the group's hold over 99% of the territory it once claimed as part of its so-called caliphate," he said.
"We have ensured Isis no longer holds the innocent people of Syria or Iraq in its murderous iron fist."