The U.S-backed Syrian fighters who drove the Islamic State group from its last strongholds are calling for an international tribunal to prosecute hundreds of foreigners rounded up in the nearly five-year campaign against the extremists.

The administration affiliated with the Kurdish-led Syrian Democratic Forces said Monday such a tribunal is needed "for justice to take its course," particularly after countries have refused to bring home their detained nationals. The SDF has detained more than 1,000 foreign fighters, including many from Western countries.

The SDF has been fighting IS since 2014 and has retaken large areas in northern and eastern Syria. Its administration is not recognized internationally or by the Syrian government, which has vowed to bring all the country's territory back under its control.