Thousands of people could still be left inside Islamic State's last enclave in eastern Syria, the US-backed Syrian Democratic Forces (SDF) said, as the waves of evacuations from the tiny area continued on Thursday.

The SDF has said it wants to ensure all civilians have been evacuated before launching a final assault on the besieged enclave of Baghouz. It is the last shred of populated territory held by Islamic State, which once controlled swathes of Iraq and Syria.

‘We are still hearing about the presence of thousands inside Baghouz,’ SDF spokesman Mustafa Bali told al-Hadath television.

‘We expect a fierce battle later on after the end of the civilian evacuation, given that those that will remain in Baghouz are the ones brimming with salafi jihadi ideology and the ones for whom surrender is not an option,’ he said.

Even with its defeat at Baghouz looming large, Islamic State is still widely assessed to represent a security threat, with a foothold in patches of remote territory and the ability to mount guerrilla attacks.

Many thousands of people, many of them the families of Islamic State fighters, have poured out of Baghouz over the last several weeks. Hundreds of Islamic State militants have also surrendered, the SDF says.

The SDF announced it was launching a final battle for the enclave last month but has slowed its attack to allow civilians to leave.

SDF commander Adnan Afrin said on Thursday he hoped the evacuations would ‘be completed today’.

On Wednesday the Syrian Observatory for Human Rights that monitors the war said preparations were underway in eastern Syria to announce the end of Islamic State there. But Colonel Sean Ryan, spokesman for the US-led coalition backing the SDF, said the international force had ‘learned not to put any timetables on the last battle’.

Islamic State suffered its major military defeats in 2017 when it was driven from the Iraqi city of Mosul and its Syrian headquarters at Raqqa by local forces supported by a US-led international coalition.