Armed opposition groups in Syria are using child soldiers in front-line combat positions, Human Rights Watch said.
Groups such as Isis, currently gaining territory from the Iraqi army in neighbouring Syria, have been "aggressively" enticing teenage boys to join their ranks as they attempt to topple Assad.
Zama Coursen-Neff, from the Children's Rights Division of Human Rights Watch said:
"Extremist groups, have aggressively targeted children and enticed them to join.
"It is bad enough that the Syrian government is dropping bombs on children. Armed opposition groups in Syria should not in turn be sending children into harms way".
Human Rights Watch spoke to several current or former child soldiers within Syria, who described their experiences.
The Foreign Secretary has been clear on the threat of Isis, but he has ruled out the prospect of any UK military involvement in the crisis.
Iraq’s foreign minister, Hoshyar Zebari, is a natural diplomat. Polite, immaculately dressed, and blessed with a great memory.
Isis has paraded military equipment in Mosul it captured from when the Iraqi army fled in what some see as a "nightmare scenario."