Syria's Kurdish fighters urge world to take back foreign militants

Syria's Kurds warned on Sunday that the thousands of foreign militants they have detained in their fight against the Islamic State group are a time-bomb the international community urgently needs to defuse.

Speaking a day after Kurdish-led forces announced the final demise of the militants' physical "caliphate", the Kurdish administration's top foreign affairs official Abdel Karim Omar warned that its foreign captives still pose a threat.

"There are thousands of fighters, children and women and from 54 countries, not including Iraqis and Syrians, who are a serious burden and danger for us and for the international community," Omar told said.

"Numbers increased massively during the last 20 days of the Baghouz operation," he said, referring to the village by the Euphrates where diehard militants made a bloody last stand.

The fate of foreign IS fighers has become a major issue as the Kurdish-led Syrian Democratic Forces closed in on the once-sprawling proto-state the militants declared in 2014.

After a months-long assault by the US-backed SDF to flush out the last IS strongholds in the Euphrates Valley, militants and their families gradually gathered in Baghouz as the last rump of the "caliphate" shrank around them.

While some managed to escape, many of the foreigners stayed behind, either surrendering to the SDF or fighting to the death.

According to the SDF, 66,000 people left the last IS pocket since January, including 5,000 militants and 24,000 of their relatives.

The assault was paused multiple times as the SDF opened humanitarian corridors for people evacuating the besieged enclave.

The droves of people scrambling out of Baghouz in recent weeks were screened by the SDF and dispatched to camps further north, where most are still held.

The de facto autonomous Kurdish administration is northeastern Syria has warned it does not have capacity to detain so many people, let alone put them on trial.

But many of the suspected militants' countries of origin are reluctant to take them back due to potential security risks and a likely public backlash.

Some have even withdrawn citizenship from their nationals detained in Syria.

"There has to be coordination between us and the international community to address this danger," Abdel Karim Omar said.

"There are thousands of children who have been raised according to IS ideology," he added. 

"If these children are not reeducated and reintegrated in their societies of origin, they are potential future terrorists."