The United Nations' human rights chief says Syrian authorities are deliberately and systematically targeting children describing their treatment as horrendous.
Navi Pillay says she is deeply concerned about the fate of hundreds of children being held in detention.
Speaking to the BBC, Mrs Pillay said President, Bashar al-Assad, could end the detentions and stop the killing of civilians immediately, simply by issuing an order.
Mrs Pillay says the Syrian leader will face justice for the abuses carried out by his security forces.
Her comments came as Syria accepted a peace plan, amid scepticism about its intentions.
The peace plan was put forward by the UN and Arab League envoy Kofi Annan.