The US-backed Syrian Democratic Forces said on Saturday it had begun the “final battle” to oust the militant Islamic State group from the last scrap of territory it holds in eastern Syria.

Backed by air strikes by the US-led coalition against IS, the Kurdish-Arab alliance has in recent months cornered the militants in a final patch of territory in the eastern province of Deir Ezzor.

After a pause of more than a week to allow civilians to flee, the SDF said on Saturday it had resumed the fight to seize the last four-square-kilometre (one-square-mile) patch from the militants.

“The SDF have launched the final battle to crush IS... in the village of Baghouz,” the SDF said in a statement.

“After ten days of evacuating more than 20,000 civilians... the battle was launched tonight to exterminate the last remnants of the organisation,” it said.

SDF spokesman Mustafa Bali told AFP: “The battle has started.”

Bali said there could be up to 600 IS fighters still inside the pocket, most of them foreigners. Hundreds of civilians are also believed to be inside.

“This battle will be sealed in the coming days,” he said.

IS overran large parts of Syria and neighbouring Iraq in 2014, declaring a “caliphate” in areas it controlled. A series of assaults have left that proto-state in tatters.

More than 37,000 people, mostly wives and children of fighters, have fled IS territory since the SDF intensified its offensive in December, according to the Syrian Observatory for Human Rights.

The Britain-based war monitor has said that figure includes some 3,200 suspected militants.