In and around the notorious al-Hol camp which has housed many families of alleged terrorists since the defeat of the Islamic State in Syria and neighbouring Iraq, "there are more than 22,000 foreign children of at least 60 nationalities who languish in camps and prisons, in addition to many thousands of Syrian children", Xinhua news agency quoted Unicef's regional director for the Middle East and North Africa, Ted Chaiban, as saying on Sunday. 

According to the UN, a fire broke out on Saturday evening during a family gathering among displaced Syrian camp residents. 

One woman reportedly died along with the three children, and at least 11 adults were injured. 

At least 20 people overall remain in hospital, with six reported to be in critical condition. 

"Children in al-Hol are faced not only with the stigma they are living with, but also with very difficult living conditions where basic service is scarce or in some cases unavailable," said Chaiban. 

"The detention of children is a measure of last resort and should be for the shortest time possible. Children should not be detained based solely on suspected family ties with armed groups or the membership of family members in armed groups." 

Last month, independent UN human rights experts noted that an "unknown number" of foreign nationals had died in the squalid camp of al-Hol and Roj, in northeast Syria, urging their home countries to repatriate their citizens as soon as possible, dismissing claims that it was too difficult to deal with the non-State groups controlling the local area. 

Chaiban said member states should do everything possible to reintegrate the children into their own societies and repatriate them in a "safe and dignified way". 

"We call on all member states to provide children -- who are their citizens or born to their nationals -- with civil documentation to prevent statelessness. This is in line with the best interests of the child and in compliance with international standards," he added. 

With almost 62,000 residents, al-Hol is the largest camp for displaced people in Syria. 

More than 80 per cent of the population are women and children. 

Accidental fires are not uncommon in the camp, with families often resorting to using cooking stoves inside their tents for warmth, particularly during winter when temperatures regularly drop below freezing, according to UN sources.