US-backed fighters battling to oust ISIL from the Syrian city of Raqqa were nearing the "final week" of their assault, the campaign's commander said on Sunday.
The Kurdish-led Syrian Democratic Forces alliance has captured around 90 per cent of ISIL's one-time bastion and are closing in on the extremists in a pocket of territory near Raqqa city centre.
The SDF's Kurdish and Arab fighters are advancing on ISIL-held districts from two fronts in the city's north and east, said 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 Raqqa," she said on the western outskirts of Raqqa on Sunday.
"Within three to four days, we will be able to take the decision to begin the final campaign."
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Ms Felat said fighting was still fierce along the front line, with ISIL using snipers, suicide bombers and reinforced positions in tunnels to hold up the SDF advance.
The extremists still hold Raqqa's national hospital, the nearby football stadium and surrounding residential neighbourhoods.
SDF fighters have surrounded the hospital and were on Sunday preparing a fresh push around the stadium further north, said Ali Sher, a field commander with the Kurdish People's Protection Units (YPG), which make up the bulk of the SDF.
"We will advance at night on foot into new positions around the stadium's north. It will be the first time we use this military tactic in Raqa," Mr Sher said.
As he spoke, Mr Sher fed bullets into a rifle magazine in one of several bombed-out apartment buildings taken up by his fighters to monitor different parts of the stadium.
One room provided a clear view of the field's edge and surrounding buildings.
An anti-ISIL sniper lay flat on furniture piled in a corner, peering out of a melon-sized hole in the wall, his finger on the trigger.
Another building overlooked the stadium's abandoned entrance. SDF members said they expected ISIL fighters were holed up in the complex's seating or underground rooms.
"The battle is in its final steps. When we finish with the area north of the stadium, we'll be able to attack it and reach Al Naim," Mr Sher said.
Al Naim roundabout in Raqqa became infamous for the public beheadings and crucifixions ISIL staged there during its three-year rule in the city.
Elsewhere in Syria on Sunday, ISIL fighters expelled Syrian regime forces from the eastern town of Mayadeen, days after they entered the key remaining extremist stronghold, a Britain-based monitor said.
Backed by Russian air power, regime forces had managed to fight their way into western Mayadeen on Friday.
"Counteroffensives by IS managed to force the regime fighters away from the western outskirts of Mayadeen," the Syrian Observatory for Human Rights said.
Observatory chief Rami Abdel Rahman said the Syrian forces were now some six kilometres from the town, which was being targeted by "intensive air strikes carried out by both regime and Russian aircraft".
ISIL has controlled Mayadeen in Syria's eastern province of Deir Ezzor since 2014.
The town is on the western bank of the Euphrates River, between provincial capital Deir Ezzor, where the extremists still hold several districts, and the border with Iraq.