France's top minors' rights watchdog urged the French government not to leave hundreds of children living unsupervised in a refugee slum outside Calais without proper shelter.
French authorities are now tearing down nearly half of the camp that is known as the "Jungle" and hosts thousands of refugees who fled war and poverty in the Middle East, Africa and Asia.
Genevieve Avenard, a state-appointed official whose job is to alert authorities of threats to minors' rights but lacks enforcement powers, called on the Calais regional government to build by this summer a shelter for the 326 children who authorities say currently live on their own in the "Jungle".
Local refugee associations say the number of children in the camp - some of whom are as young as seven years old - tops 500 and more when including those living with their parents.
"Most of these kids only want to go to Britain. If you take them away, they'll come back," Avenard told Reuters in an interview. "We are still in the dark when it comes to assessing exactly who these children are and hence what can be done for them."
Avenard said unaccompanied minors identified so far were mostly from Afghanistan, Eritrea, Sudan and Syria.
A French administrative court ordered the Calais government in November to identify all minors in the camp and transfer them to child welfare centres. But carrying out the tally has proven difficult as new refugee families keep arriving.
"We need to understand these children, listen to them and make sure we can implement specific policies such as asylum or family reunions in Britain when possible," said Avenard.
Around 90 children have the right to enter Britain legally because of family members who are already there, she added.
Earlier this month, President Francois Hollande said during a Britain-France summit that children in Calais with family ties to Britain should be allowed to travel across the Channel "quickly and efficiently."
British policy is generally to take in war refugees, such as Syrians, only from outside Europe as officials believe that to receive people who have already made it to Calais would simply increase the flow of "economic" migrants.
A spokesman for the Calais regional government was not immediately available for comment.