UN Human Rights Commissioner, Navi Pillay
Syrian authorities are systematically detaining and torturing children, the United Nations' human rights chief, Navi Pillay, has told the BBC.
Ms Pillay said President Bashar al-Assad could end the detentions and stop the killing of civilians immediately, simply by issuing an order.
Syria has accepted a peace plan, amid scepticism about its intentions.
Most opposition groups have now agreed that the Syrian National Council will formally represent the Syrian people.
Navi Pillay, in an interview with the BBC before Syria accepted the plan, said the Syrian leader would face justice for the abuses carried out by his security forces.
Asked if President Assad bore command responsibility for the abuses, she said: "That is the legal situation. Factually there is enough evidence pointing to the fact that many of these acts are committed by the security forces [and] must have received the approval or the complicity at the highest level.
"Because President Assad could simply issue an order to stop the killings and the killings would stop."
Ms Pillay said she believed that the UN Security Council had enough reliable information to warrant referring Syria to the International Criminal Court (ICC).
"I feel that investigation and prosecution is a crucial element to deter and call a stop to these violations," she said.
She listed what she called "horrendous" treatment of children during the unrest.
"They've gone for the children - for whatever purposes - in large numbers. Hundreds detained and tortured... it's just horrendous," she said.
"Children shot in the knees, held together with adults in really inhumane conditions, denied medical treatment for their injuries, either held as hostages or as sources of information."
Ms Pillay said anyone who committed such violations would be held to account.
"There is no statute of limitations so people like [Assad] can go on for a very long time but one day they will have to face justice."
The UN says more than 9,000 people have been killed since the uprising against President Assad began a year ago.
Late on Tuesday, several Syrian dissident groups meeting in Istanbul agreed to recognise the Syrian National Council as the official representative of the Syrian people.