Secretary of State Antony Blinken has demanded that US allies return citizens arrested abroad for joining ISIS, warning that they cannot stay in Syria indefinitely, AFP reported.

Blinken launched the call in Rome at a meeting of a coalition of 83 members to fight ISIS.

The US estimates that some 10,000 suspected Islamic State fighters are being held in northern Syria by Kurdish militants allied with the West. 

According to Blinken, the United States continues to urge countries, including coalition partners, to repatriate, rehabilitate and, where necessary, prosecute their citizens.

France and the UK, two of the US closest allies, have resisted calls for the return of their citizens, which were also made by the administration of former President Donald Trump. Both countries have had painful experiences of attacks and see little incentive for the return of radicalized citizens who are already in jails abroad.

Blinken praised Italy as one of the few Western European countries to repatriate their citizens, and also welcomed the efforts of Central Asian countries such as Kazakhstan, which he said have returned 600 militants and their families.