A new United Nations report claims President Bashar Assad's forces tortured, maimed, and sexually abused children, while rebels recruited many for combat.
Accusations including the arbitrary detention and arrests of children were also detailed, with evidence showing that children as young as 11 years old were detained on suspicion of having associations with armed groups.
Some children in government custody have reportedly suffered beatings with metal cables, whips, and wooden and metal batons.
Others were punished by electric shock and sexual violence, including rape or threats of rape, mock executions, cigarette burns, sleep deprivation, and solitary confinement.
"Armed opposition groups also engaged in the summary execution of children," the report said.
Allegations of children being used as human shields by Assad's forces were also detailed.
The report covered the treatment of children from the beginning of the uprising against Assad in March 2011 until November 2013.
U.N. Secretary General Ban Ki-moon urged the two sides to "take, without delay, all measures to protect and uphold rights of all children in Syria."
Meanwhile, the Syrian government missed Wednesday's deadline to give up its stockpile of chemical weapons.
The chemical removal timetable set up by the Organization for the Prohibition of Chemical Weapons is now several weeks behind schedule.
Reports claim the Syrian government is trying to hide some of its arsenal. The United States said the Assad regime is just dragging its feet.
''I do not know what the Syrian government's motives are, or if it was incompetence, or why they are behind on delivering these materials. What we do know is they are behind, and what we do know; they need to fix this," U.S. Secretary of Defence Chuck Hagel said.
The Syrian government said it will still meet the deadline of destroying all of Syria's chemical weapons by June 30.