Egyptian authorities arrested more than 300 children during protests in Cairo over the past year, beating and torturing some and trying many as adults, a leading international rights group said Tuesday.
Human Rights Watch said in a report that the arrests and treatment of detained children violated Egyptian and international law.
Clashes resumed Tuesday in downtown Cairo at the site of a bloody confrontation a year ago between protesters and the military.
The New York-based group says the detentions occurred during protests against harsh measures imposed by the military in the wake of last year's uprising that toppled Hosni Mubarak. The military took over after Mubarak stepped down, running the country until a new president took office at the end of June.
The group said it interviewed children who had been detained. They said police and military officers "kicked them, beat them with rifle butts, hit them with batons and subjected them to electric shocks."
It also said police interrogated children before they had access to a lawyer and sent juveniles to be tried as adults, in violation of Egyptian and international law.
Human Rights Watch said its interviews of relatives and the lawyers of children who were arrested over the past year showed that police consistently carried out widespread arrests during protests. It said violations against children were linked to five major protests in the aftermath of the uprising.
More recently, the group said that at least 136 children were arrested during September demonstrations against an anti-Muslim film that sparked violence in the Middle East. The arrests, made in front of the U.S. Embassy in Cairo, were the largest single roundup of children linked to a protest in the past year.
Human Rights Watch said that President Mohammed Morsi took a positive step last month when he issued a pardon for those charged or convicted of acts "in support of the revolution." It said Morsi must now investigate abuse that protesters suffered while in state custody, and make cases involving children a priority.
In downtown Cairo, protesters clashed with security forces for the second day in demonstrations to mark the anniversary of a violent series of confrontations that left 42 people dead.
On Tuesday, scores of masked protesters hurled stones and firebombs at security forces, who responded by firing birdshot and tear gas. Security officials said dozens were injured over two days of clashes, and 19 people were arrested. The officials spoke on condition of anonymity because they were not authorized to speak to reporters.
The two sides clashed at a school that was taken over by security forces. Field hospitals were set up on a side street.
Protester Loai al-Qahwagi, who had scratches on his forehead, said that the spark of the latest violence was "the state of anger and frustration among youth who saw no retribution for the killings during last year's protests."
"Explosions of anger and violence will keep recurring as long as there is no justice," he said.