'Toughest fighting yet' to oust IS from Syria's Raqa

The US-backed force fighting to oust the Islamic State group from its former Syrian stronghold Raqa said Monday it was waging its "toughest battles yet", as the city's capture neared.

The Syrian Democratic Forces, an alliance of Kurdish and Arab fighters, broke into Raqa in June and are now poised to seize the last 10 percent of the city, dealing the jihadists a major blow.

"The Syrian Democratic Forces are currently waging their toughest battles yet," Jihan Sheikh Ahmed, spokeswoman for the operation to capture the city, told AFP.

The latest fighting "will bring an end to Daesh's presence, meaning they can choose between surrendering and dying," she added, using the Arabic acronym for IS.

An estimated 300 mostly foreign IS fighters are essentially surrounded but are expected to make a fierce last stand.

"The IS elements that are still there are resisting," Sheikh Ahmed said, adding that the neighbourhoods where fighting is under way "are fortified and heavily mined areas."

Overnight, SDF fighters captured the northern Al-Barid neighbourhood, and their efforts would focus Monday on the several adjacent districts, she added.

On Sunday, the SDF announced the "final phase" of the battle for the city, with a resumption of fighting after a pause to negotiate the safe exit of civilians and the surrender of some IS fighters.

In a statement, the militia said that the last phase of the fighting would "end the presence of the terrorist mercenaries inside the city".

"The battle... will continue until the entire city is cleared of terrorists who refuse to surrender, including foreign terrorists."

On Monday, an AFP reporter in west Raqa heard intermittent cannon fire, but said the city was largely quiet, with no sign of the groups of fleeing civilians that have often been seen leaving in recent weeks.

- Civilian exodus -

SDF spokesman Talal Sello told AFP on Sunday that the city was virtually empty of civilians after 3,000 left Saturday night as part of a deal agreed between local officials and Syrian IS fighters.

"Only 250 to 300 foreign terrorists who refused the deal and decided to stay and fight until the end remain in the city, and relatives of some members are with them," he said, without specifying the number of civilians.

Under the deal, a total of 275 Syrian IS fighters and relatives surrendered to the SDF, though it was unclear whether they would be given safe passage elsewhere.

There had been speculation for days about a deal to allow the SDF to capture the last parts of the city while preventing further civilian casualties.

But there were contradictory reports about whether the deal would allow foreign IS fighters to leave, something that has been strongly opposed by the US-led coalition supporting the SDF.

"We're very adamant about not allowing foreign fighters to leave the city," coalition spokesman Colonel Ryan Dillon told AFP on Sunday.

"Our stance was they either stay and fight or they surrender unconditionally."

The Raqa Civil Council that negotiated the deal has denied any foreign IS fighters were allowed to leave.

IS captured Raqa in 2014. Under its rule the city become synonymous with the jihadist group's worst abuses and was transformed into a planning centre for attacks abroad.

The city's recapture would be only the latest blow for IS, which has suffered a string of setbacks in recent months.

It was driven from its largest Iraqi stronghold Mosul in July and now only controls a fraction of the self-styled "caliphate" it proclaimed more than three years ago and once covered territory roughly the size of Britain.

In Syria, its presence is largely confined to the eastern province of Deir Ezzor, where it is under attack by both the SDF and a Russia-backed Syrian government campaign.