"Living conditions remain deplorable," the Inquiry Commission on Syria said in it latest report to the UN Human Rights Council in Geneva, describing developments between January and July.
Children died from malnutrition and untreated wounds, while the camp's total population of about 70,000 people has also suffered from flooding, infectious diseases and lack of food, the investigators found.
They warned countries that hindering the repatriation of Islamic-State-linked women and their 3,500 children from al-Hol only creates further problem.
"Women and children remain at higher risk of further radicalization, especially given the absence of age and gender-sensitive rehabilitation programmes" in the camp, the report said.
Commission chairman Paulo Pinheiro also criticized governments that are trying to bring so-called Islamic State children back from Syria while leaving mothers behind.
"Member state policies aimed at repatriating children without their mothers is also something which runs counter to the principle of 'best interests of the child,'" he said.
Beyond al-Hol, the SDF holds thousands of children above the age of 12 in detention along with adults who are suspected of being Islamic State fighters, according to the report.
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