GENEVA — A U.N. human rights panel said Friday it has called on Syria to respond to reports of its security forces torturing children in their crackdown against anti-government protesters.

The Committee against Torture said it had received "numerous, consistent and substantiated reports" of widespread abuse occurring since the start of the uprising against President Bashar Assad's government eight months ago.

"Of particular concern are reports referring to children who have suffered torture and mutilation while detained," said the panel's chairman, Claudio Grossman.

He also cited reports of "extrajudicial, summary or arbitrary executions; arbitrary detention by police forces and the military; and enforced and involuntary disappearances."

The committee normally reviews each country's record every four years, but took the unusual step Friday of issuing a spontaneous demand to the Syrian government to explain its actions.

Syria has become largely isolated in recent months as the international community, including its Arab neighbours, have condemned the bloody suppression of protests that began peacefully but have since turned increasingly violent. The U.N. human rights office says more than 3,500 people have been killed since March.

Grossman said there was no doubt that the Syrian government was responsible for the abuse of regime opponents, including those not actively participating in protests.

"These violations are conducted under order from public authorities, or with consent and acquiescence," he said. "They have not taken place only against people demonstrating. There have been detentions of individuals who are opposing the regime, whether they are demonstrating or not demonstrating."