Britain said on Wednesday it had repatriated a child from Syria, one of dozens of British children thought to be trapped in the war-torn country.

British officials have previously faced criticism for refusing to help nationals including children to return home after they or their parents were accused of joining the Islamic State militant group.

"Pleased we have been able to bring home a British child from Syria," British Foreign Secretary Dominic Raab said on Twitter.

"Safely facilitating the return of orphans or unaccompanied British children, where possible, is the right thing to do."

The foreign ministry declined to provide further details, citing reporting restrictions on cases involving minors.

Save the Children said in a report last year that more than 60 British children were stranded in northeast Syria.

The UK has taken a strict approach, stripping citizenship from some of those suspected of travelling to support the IS group.

Among the most high profile cases is that of Shamima Begum who was 15 when she and two other schoolgirls from east London left to join the jihadist group in 2015.

She claims to have married a Dutch convert soon after arriving in IS-held territory who subsequently died.

Begum, now 20 and marooned in a refugee camp, was discovered nine months pregnant in another camp in February last year, and her newborn baby died soon after she gave birth. Two of her other children also died under IS rule.

Britain annulled her UK citizenship on national security grounds after an outcry led by right-wing media but Begum has mounted a legal challenge of the decision.

The UK Supreme Court is set to decide on whether she can return to Britain to fight the case in court.