General Michael Kurilla met United States military commanders and the Syrian Democratic Forces (SDF) on Thursday "to get an assessment" of efforts to defeat IS and prevent its regional resurgence, as well as "the evolving situation in Syria", a CENTCOM statement said.

The US and other Western countries as well as Syria's neighbours have emphasised the need for the country's new rulers to combat "terrorism and extremism".

Supported by the US, the SDF spearheaded the military campaign that ousted Islamic State (IS) group jihadists from Syria in 2019 and controls dozens of prisons and camps where thousands of militants and their suspected relatives, including foreigners, are held.

CENTCOM, which oversees US military operations in the Middle East, said Kurilla visited the Al-Hol camp which, together with a smaller facility, houses more than 40,000 people, many of them with ties to IS.

It added that "without international repatriation, rehabilitation, and reintegration efforts," such camps "risk creating the next generation" of IS members.

An additional 9,000 IS detainees "from over 50 different countries remain in over a dozen SDF guarded detention facilities in Syria", CENTCOM said.

Neighbouring Turkey, a key backer of Islamist-led rebels who ousted longtime Syrian ruler Bashar al-Assad last month, sees the main component of the SDF, the YPG People's Protection Units, as affiliated with the Kurdistan Workers Party (PKK).

Both Turkey and the United States consider the PKK a "terrorist" group. It has waged a decades-long insurgency on Turkish soil.