"Today (Thursday), around 40 Russian children will be transferred to a Russian government delegation," the official told AFP, speaking on condition of anonymity.

Authorities are to hold a press conference later Thursday about the returns.

The Kurdish administration holds thousands of Syrians and foreigners with alleged ties to the Islamic State group in its custody, after spearheading a US-backed campaign that stripped IS of its last territory in Syria in 2019.

Alleged foreign fighters are held in jails, while women and children with ties to the group live in camps for the displaced.

The Russian repatriations follow a similar move by France, which announced it had repatriated 40 children and 15 women from camps in Syria Thursday.

Syria's Kurds have repeatedly urged the international community to repatriate foreign nationals held in overcrowded camps.

But their calls have largely fallen on deaf ears with only limited numbers, mostly children, allowed to return as home countries fear security threats and a domestic political backlash.

Nearly 4,500 Russians went to fight alongside IS, and Moscow was the first to organise returns from Syria and also Iraq.

At least 341 Russians, many of them orphans, were repatriated between 2018 and late 2021, following the first returns of women and children spearheaded by Chechen President Ramzan Kadyrov.