Fight to drive IS from Raqa nears end

US-backed fighters say they are nearing the "final week" of their assault to drive the Islamic State group from their one-time Syrian bastion Raqa, as the jihadists' self-described caliphate crumbles.

Losing Raqa would be only the latest in a series of crushing defeats for the extremist group, which once controlled large swathes of territory spanning the border between Syria and Iraq.

Captured by IS in 2014, the northern city was the de facto Syrian capital of the jihadists' self-styled "caliphate" until the US-backed assault by the Syrian Democratic Forces, an alliance of Kurdish and Arab fighters.

The militia has captured around 90 percent of Raqa since entering the city in June, after months of fighting to encircle it.

A woman and her daugther get some rest after they cross the Cilvegozu border gate, entering Turkey in Hatay. Turkish army has launched a reconnaissance mission in jihadist-controlled northwestern Idlib province in a bid to create a de-escalation zone. Photo: Reuters, AFP

They are now advancing on IS-held districts from two fronts in the city's north and east, said commander Rojda Felat, who heads the "Wrath of the Euphrates" campaign.

"If the two fronts meet, we can say we have entered the final week of our campaign to liberate Raqa," Felat told AFP on the western outskirts of Raqa on Sunday.

"Within three to four days, we will be able to take the decision to begin the final campaign," she added.

Felat said fighting was still fierce along the front line, with IS using snipers, suicide bombers and reinforced positions in tunnels to hold up the SDF advance.

The jihadists still hold Raqa's national hospital, the nearby football stadium and surrounding residential neighbourhoods, including the infamous Al-Naim roundabout, where IS staged public beheadings and crucifixions.