"It has been an urgent matter for months. We have been with those children in northeastern Syria for months. It is already late and every day that passes makes it even later," Fran Equiza told Efe news on the phone.
"Despite all efforts of humanitar to provide the best services to children, the conditions are clearly not of an environment they can develop in."
The children should be sent back "as quickly as possible in accordance with regulations and legality and in the best interest of the children", Equiza added.
lmost 28,000 children from over 60 different countries, including nearly 20,000 Iraqis, were trapped in the northeast, mostly in displacement camps, according to the Unicef.
More than 80 per cent were under the age of 12 and 50 per cent below five years.
The camps are under the control of Kurdish authorities and Syrian Democratic Forces, the Kurdish-led militia that fought in the final battle against the Islamic State (IS) terror group in Syria.
Unicef estimated that at least 250 children, some as young as nine years old, were held in detention centres, adding that the actual numbers were likely to be higher.
re accused of having links to the Islamic State Terrorist Organization.
Equiza pointed out that repatriation must be held voluntarily, as at least 17 governments had repatriated over 650 children to their home countries.
The offensive Turkey launched on October 9 in northeastern Syria, where camps and detention centres are located, has left more than 200,000 others, mostly children and women, displaced.
( With inputs from IANS )