Syria's Kurds said they handed over a Sudanese woman accused of belonging to the "Islamic State of Iraq and Syria" (ISIS) and her baby to a Sudanese diplomat Thursday (September 20th), AFP reported.

Kurdish authorities controlling swathes of northeastern Syria have detained hundreds of alleged ISIS members from dozens of countries since the group's so-called caliphate crumbled last year.

But their home countries have been overwhelmingly reluctant to claim them, with public opinion hostile to repatriating them.

On Thursday, the Kurdish authorities in northeast Syria delivered a Sudanese woman and her one-month-old baby to a Sudanese diplomat in Qamishli.

The Kurds "decided to hand her over to her country's embassy" after Khartoum requested the transfer, Kurdish foreign affairs official Abdel Karim Omar said.

Kurdish fighters have formed the backbone of the Syrian Democratic Forces (SDF), an alliance backed by the international coalition that has expelled ISIS from swathes of the country.

"Around 520 ISIS mercenaries, as well as 550 women and around 1,200 children from 44 countries" are still in Kurdish custody, Omar said.

"It is a heavy burden that we cannot carry alone," he said.

The fate of foreign fighters captured in Syria remains controversial, with only rare countries agreeing to take them back.

"We will not try any ISIS fighter," Omar said. "We are trying as much as possible... to pressure governments to carry out their duties and take their citizens back."