Syrian Democratic Forces fighters, seen here on the Baghouz frontline, have spearheaded the ground battle against IS in Syria
Qamishli (Syria) (AFP) - The US-backed Syrian Democratic Forces said Saturday it had begun the "final battle" to oust the Islamic State group from the last scrap of territory it holds in eastern Syria.
IS overran large parts of the country and neighbouring Iraq in 2014, declaring a "caliphate" there, but various military offensives have reduced it to a fragment.
Backed by air strikes of the US-led coalition against IS, the Kurdish-Arab alliance has in recent months cornered the jihadists in a final pocket of territory in Syria's eastern province of Deir Ezzor.
After a pause of more than a week to allow civilians to flee, the SDF said Saturday it had resumed the fight to seize the last four-square-kilometre (one-square-mile) patch from the jihadists.
"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 wipe out the last remnants of the organisation, it said.
SDF spokesman Mustafa Bali told AFP: "The battle has started."
"This battle will be sealed in the coming days," he added.
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.
"We have special units whose job it is to direct civilians to corridors they can cross" to safety, he said.
- 'Slow progress' -
Near the battlefield, an SDF spokesman at the Omar oil field turned military base said "progress is slow".
He said that when the SDF detects movement from IS fighters, they bomb them, but added: "There have not been any major changes."
At the height of its rule, IS controlled territory the size of Britain.
But a series of separate military operations, including by the SDF, have left its proto-state in tatters.
On Thursday, the coalition said the "caliphate" had massively shrunk.
Major General Christopher Ghika, the coalition's deputy commander, described the size of the last IS pocket as "now less than one percent of the original caliphate".
More than 37,000 people, mostly wives and children of jihadist 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 jihadists.
Bali, of the SDF, said that "in the last two months, most who handed themselves in or were arrested were foreign".
The SDF launched an operation to expel IS from Deir Ezzor in September, and has slowly advanced against IS despite the jihadists putting up a fierce fightback.
In that time, more than 1,200 IS militants, more than 670 SDF fighters, and around 400 civilians have been killed in the fighting, the Observatory says.
The Kurdish People's Protection Units (YPG) and their female equivalent, the Women's Protection Units (YPJ), have formed the backbone of the SDF.
- Female fighter's funeral -
In the northeastern Kurdish-majority city of Qamishli on Saturday, SDF fighters stood to attention at the funeral of a YPJ fighter who died fighting IS.
Fellow combatants carried a coffin draped in the Kurdish colours of red, yellow and green, covered in pink flowers and adorned with a picture of the young woman.
Near her coffin, a mourner held up a doll dressed in a bridal gown, part of tradition for young women fighters who die before they are married.
Despite its "caliphate" being on the brink of collapse, IS still retains a presence in Syria's vast Badia desert and has carried out deadly attacks in SDF-held territory.
Syria's war has killed more than 360,000 people and displaced millions since it erupted in 2011 with the brutal repression of anti-government protests.
The country's Kurds have largely stayed out of the conflict, instead developing semi-autonomous institutions in parts of the country's northeast under their control.
Neighbouring Turkey sees Syrian Kurdish fighters as "terrorists" and has repeatedly threatened to attack YPG-held areas along its southern border.
The US military presence in Syria has offered the Kurds a measure of protection against any Turkish offensive.
But in December Washington announced it would pull out all its troops from Syria, sending Kurdish authorities scrambling to mend fences with the regime in Damascus.
Almost eight years into the war, President Bashar al-Assad's regime has advanced against rebels and jihadists, and holds nearly two-thirds of the country.
Damascus has rejected Kurdish self-rule, and has said it would eventually return the oil-rich third of the country now beld by the SDF to government control.