AIN ISSA, Syria/BEIRUT: Daesh is on the verge of defeat in Syria's Raqqa and the city may finally be cleared of the militants on Saturday or Sunday, the Syrian Kurdish YPG militia told Reuters.

This comes as U.S.-backed Syrian Democratic Forces says the final battle for Raqqa is underway. A spokesman for the Kurdish militia that forms the backbone of the SDF, Nouri Mahmoud, says Daesh extremists still in Raqqa are mostly suicide bombers and special units that go behind enemy lines.

The U.S.-led coalition fighting Daesh said the militants remaining in the Syrian city of Raqqa are likely left with only small arms to fight for the sliver of land they still control there.

The coalition said in a statement emailed to AP that Daesh militants still in Raqqa are completely cut off from their leadership and likely have only pistols, rifles, light machine guns and a dwindling supply of ammunition,

Despite this assessment, the coalition says it expects difficult days ahead until Raqqa, once the militants' de facto capital, is retaken. Earlier this week, the coalition estimated that 300 to 400 militants remained in the city. On Friday, a local official said an estimated 100 militants surrendered in the last 24 hours.

The Syrian Observatory for Human Rights said remaining Daesh fighters were being transported out of Raqqa by bus under a deal between Daesh, the U.S.-led coalition and the SDF, which is dominated by the YPG.

The SDF, backed by coalition air strikes and special forces, has been battling since June to oust Daesh from Raqqa city.

The final defeat of Daesh at Raqqa will be a major milestone in efforts to roll back the group's self-declared "caliphate" in Syria and Iraq, where earlier this year the group was driven from the city of Mosul.

"The battles are continuing in Raqqa city. Daesh is on the verge of being finished. Today or tomorrow the city may be liberated," YPG spokesman Nouri Mahmoud told Reuters by telephone.

In emailed comments to Reuters, coalition spokesman Ryan Dillon said around 100 Daesh fighters had surrendered in Raqqa in the last 24 hours and were "removed from the city", without giving further details.

"We still expect difficult fighting in the days ahead and will not set a time for when we think [Daesh] will be completely defeated in Raqqa," he said, adding that around 85 percent of Raqqa had been liberated as of Oct. 13.

Around 1,500 civilians had been able to safely make it to SDF lines within the last week, he added.

Omar Alloush, a member of a civilian council set up to run Raqqa, told Reuters late on Friday that efforts were under way to secure the release of civilians and "a possible way to expel terrorist elements from Raqqa province," without giving further details.

An activist group that reports on Raqqa, Raqqa Is Being Slaughtered Silently, said on its Facebook page on Saturday that dozens of buses had entered Raqqa city overnight, having travelled from the northern Raqqa countryside.

The Observatory said Syrian Daesh fighters and their families had already left the city, and buses had arrived to evacuate remaining foreign fighters and their families. It did not say where they would be taken to.

During the more than six-year Syrian war, the arrival of buses in a conflict zone has often signalled an evacuation of combatants and civilians.

The campaign against Daesh in Syria is now focused on its last major foothold in the country, the eastern province of Deir al-Zor which neighbors Iraq.

Daesh is facing separate offensives in Deir al-Zor by the SDF on one hand, and Syrian government forces supported by Iranian-backed militia and Russian air strikes on the other.

In August, Daesh fighters agreed to be evacuated from a Lebanon-Syria border area, the first time the militants had publicly agreed to a forced evacuation from territory they held in Syria.

Civilians have been making perilous journeys to escape Daesh-held areas as SDF forces advance. The SDF says it helps transport them away from the fighting after they flee.

The offensive to drive Daesh out of Raqqa has long outlasted initial predictions by SDF officials who said ahead of an assault in June that it could take just weeks.

The battle for Raqqa has taken a severe toll on civilians.

Those inside the city for months have endured miserable conditions, lacking water, power, food and healthcare.

Rights group Amnesty International, the Observatory and monitoring group Airwars say hundreds have been killed by air strikes, fighting and Daesh snipers and mines.

The coalition says it takes great pains to avoid causing civilian casualties and investigates all reports that it has done so.