Children in Syria have endured unspeakable suffering during the ongoing conflict, a report to the United Nations Security Council says.
More than 10,000 children are believed to have been killed in nearly three years of civil war and more than four million have fled their homes.
The report also documents cases of child detention, torture, murder and rape, the BBC reported.
The report, which covers the period 1 March 2011 to 15 November 2013, said in the early stages of the uprising against President Bashar al-Assad, violations were mostly committed by the Syrian military, intelligence services and pro-government militias.
Then, as the fighting intensified and the armed opposition became more organised, an increasing number committed by rebel groups were documented.
The report said children were arrested, detained with adults, ill-treated and tortured by government forces in large-scale arrest campaigns, particularly in 2011 and 2012.
Witnesses said the abuses included "beatings with metal cables, whips and wooden and metal batons; electric shocks, including to the genitals; the ripping out of fingernails and toenails; sexual violence, including rape or threats of rape; mock executions; cigarette burns; sleep deprivation; solitary confinement; and exposure to the torture of relatives".
Investigators documented reports of sexual violence perpetrated by intelligence and military personnel against children suspected of being affiliated with the opposition, the report said.
Witnesses said sexual violence was used to humiliate, harm, force confessions or pressure a relative to surrender. It reportedly included "electric shocks to, or burning of, the genitals, and the rape of boys and, in a few instances, of girls", the report said.
Meanwhile, United States Secretary of State John Kerry has condemned the use of barrel bombs in the Syrian city of Aleppo by forces loyal to President Bashar al-Assad.
Mr Kerry said it is the latest barbaric act by the Syrian regime, after using torture and chemical weapons, and blocking aid to starving communities.