Forces Comb Ghost City Raqa after IS Ouster

US-backed forces combed the ruins of Raqa for survivors and bombs Wednesday, after retaking the Syrian city from Islamic State group jihadists and dealing their dreams of statehood a fatal blow.

A lightning final assault by the Syrian Democratic Forces on Tuesday saw jihadist defences collapse faster than expected and the SDF claim a landmark victory in the three-year fight against IS.

SDF fighters flushed jihadist holdouts from Raqa's main hospital and municipal stadium, wrapping up a more than four-month offensive against what used to be the inner sanctum of IS's self-proclaimed "caliphate".

Waving their yellow flags, the Kurdish-led SDF forces celebrated their victory on an infamous traffic circle where IS used to carry out public executions and that had become known as the "Roundabout of Hell".

On Wednesday, teams of SDF fighters deployed across the eery, rubble-strewn streets of Raqa to look for unexploded ordnance and booby traps left behind by the jihadists.

"They are making sure there are no more sleeper cells" in Raqa, SDF spokesman Mustefa Bali told AFP.

"Mine-clearing operations and the re-opening of the city are under way," Bali said, adding that his organisation would only formally announce the liberation of the city once they are completed.

The SDF and the Kurdish intelligence services issued clear instructions forbidding the tens of thousands of displaced families from attempting to return to their homes.

- City unsafe -"We urge our people in Raqa who fled IS rule not to return to the city for their own security until it is rid of terrorist explosives," the Kurdish internal security services said in a statement.

The loss of Raqa left IS ruling over a small "rump caliphate" straddling the Iraqi-Syrian border and covering a fraction of the territory it held when it declared its "state" in July 2014.

The US-led coalition supporting anti-IS forces in Iraq and Syria said on Tuesday that the jihadists had lost 87 percent of the territory they had three years ago.

Brett McGurk, the White House's envoy to the multinational coalition, said on social media that IS had lost 6,000 fighters in Raqa and described the organisation as "pathetic and a lost cause."

Raqa was one of the most emblematic IS bastions, at the heart of both its military operations and its propaganda.

Several of the most high-profile attacks IS claimed in the West -- such as the 2015 massacres in Paris -- are believed to have been at least partly masterminded from Raqa, earning the city the nickname of "terror central".

Raqa also featured heavily in the propaganda videos -- from public beheadings to trainings -- which IS used to instill fear among the caliphate's residents and appeal to new recruits globally.

- Fate of IS fighters unclear -The breakthrough in the months-old operation to retake Raqa came last week when a local deal was struck for the safe exit of several thousand civilians who had been used as human shields by IS and for the surrender of Syrian jihadists.

It had been believed than up to 400 mostly foreign IS fighters remained in the city, prepared for a bloody last stand in their final redoubts.

Yet the sequence that followed the announcement on Sunday of the operation's final phase gives few clues as to their fate.

"Some surrendered, others died," Talal Sello, another SDF spokesman said, without elaborating further or providing figures.

The Syrian Observatory for Human Rights, a Britain-based monitor relying on an extensive network of sources across Syria, said most of the foreign fighters surrendered and were being held by Western intelligence services.

"They are not visible because intelligence services are detaining them," Observatory chief Rami Abdel Rahman told AFP. "French and Belgian jihadists are definitely being held by intelligence."

It was not immediately possible to corroborate his claim.

Colonel Ryan Dillon, the US-led coalition's spokesman, only spoke of four confirmed cases of foreign IS fighters surrendering and stressed that they were in SDF custody.

"We as the coalition do not hold or control any of these detainees," he said, adding that the SDF may make separate arrangements with the detained jihadists' countries of origin for some of them to be handed over and prosecuted.