ERBIL, Kurdistan Region – The Syrian Democratic Forces (SDF) have resumed their final offensive against the Islamic State (ISIS) militants corralled into a tent camp on the banks of the Euphrates River, the last corner of territory controlled by the group.

“Airplanes have targeted weapons depots of terrorists,” SDF media officer Mustafa Bali announced on Twitter Sunday evening. There is “direct fierce fighting on the outskirts of the camp.”

The offensive began at 6pm local time, he said. Two hours earlier, he had warned ISIS that time was up.

“The timeline that we [gave to] ISIS to surrender themselves is over,” he had tweeted. “Our force is now ready to start and finish what is left in ISIS hands.”

What remains of the so-called ISIS caliphate is a 500 square metre scrap of land covered in makeshift tents near the eastern Syrian village of Baghouz, a few kilometres from the border with Iraq. The militants are besieged with Kurdish-led SDF on three sides and on the fourth the Euphrates River with regime forces beyond.

Tens of thousands of civilians – including Yezidis and others who had been held captive by the jihadists for years – and ISIS family members have evacuated the Baghouz area, nearly 20,000 in the past two and a half weeks alone. Hundreds of ISIS fighters have also surrendered.

But the number of people prepared to leave tent city before it becomes a battle zone has dwindled.

On Saturday, "only about 100 people left, including three Chinese Uighurs and three Moroccan women," Bali told AFP earlier in the day.

The SDF had paused operations and opened up an escape corridor to allow the civilians to get to safety. The force does not know how many fighters remain.

"Actually we don’t know how many Daesh fighters are in Baghouz, but we do know that the remaining ones are those who really want to fight. They are those who have come from abroad such as Europe, Turkey, Iraq and Asia,” SDF spokesperson Adnan Afrin told Rudaw TV Saturday evening, using an Arabic acronym for ISIS.

The SDF is backed by jets of the US-led coalition.

Afrin estimated that the militants remaining are “not few.”

Though the area of territory is small, it is difficult to estimate how many people are in the tent camp because the group is using tunnels.

Ruadw