GENEVA (AP) — A U.N.-backed human rights advocate says hundreds of boys — some as young as 11 — held in detention camps run by U.S.-backed, Kurdish-led forces in northeastern Syria have been wrongly separated from their mothers on the “unproven" belief that they pose a security risk.

Fionnuala Ni Aolain, an independent U.N. rapporteur on the protection of rights while countering terrorism, aired concerns Friday about lingering “mass arbitrary detention” in the infamous al-Hol camp and others like it that she saw during her trip to the region this week — billed as the first visit of its kind by an independent human rights expert.

For years, human rights advocates have been calling on foreign countries — in Europe, north Africa and beyond — to repatriate their nationals from the camps housing family members of Islamic State group militants, especially children who were not involved in the atrocities carried out by the extremist group.

The group rose to power amid an uprising-turned-civil war that erupted 12 years ago and has left hundreds of thousands dead. At one point the militants controlled large swaths of Syria and Iraq, but Kurdish forces backed by an international anti-IS coalition, as well as Iraqi and Syrian government troops, recaptured that territory by 2019.

Ni Aolain said her team’s experts have calculated that since 2019, some 7,000 people have been repatriated by some 36 countries — more than three-quarters of them women and children.

But tens of thousands of others remain left behind in the detention centers — and no immediate sign of getting out, let alone traveling to the countries that they or their families came from.

Fearing that a new generation of militants will emerge from al-Hol Camp, the Kurdish officials who govern eastern and northern Syria have been experimenting with a rehabilitation program aimed at pulling children out of extremist thought — by removing them from their families and whisking them away for training in tolerance and other education.

The Kurdish officials fear that kids who grow up in the camp could give rise to a new generation of violent extremists.

Ni Aolain lashed out at the use of “dehumanization language” against so-called “Cubs of the Caliphate” — a reference to children from areas formerly under Islamic State control — “to describe 2-year-olds, 3-year-olds, 4-year-olds, 5-year-olds born on this territory by no choice of their own.”

Ni Aolain said conditions were “dire” in al-Hol, which she said was currently home to more than 49,000 people. She expressed concerns about security, access to health care, and “scarcity of water” in camps where temperatures rose to 50 degrees Celsius (122 Fahrenheit) and tents were providing shelter.

“The second issue I want to highlight is the separation of hundreds of adolescent boys from their mothers without any legal procedure, in what I describe as ‘summary separation’ based on an unproven security risk that male children pose upon reaching the age of adolescence," Ni Aolain said.

“Every single woman I spoke to made clear that it was the snatching of the children that provided the most anxiety, the most suffering, the most psychological harm,” she said, alluding to the ”distress" felt by many of the boys.

“The taking of these boys may in itself constitute a disappearance practice under international law, which is in direct contravention of multiple human rights obligations,” said Ni Aolain, who is faculty director of the Human Rights Center at the University of Minnesota Law School.