Recruiters of child soldiers should face prosecution by the international criminal court, a human rights group has said.
Child soldiers have been used in 22 conflicts in the last three years
The Coalition to Stop the Use of Child Soldiers (CSUCS) has called on the UN to name, shame and pursue armies and militias which use children to fight.
Fighters under the age of 18 have been used in 22 conflicts in the last three years, it reveals in a new report.
It says the US and UK were among countries recruiting underage soldiers.
In the early stages of the Afghanistan and Iraq campaigns, up to 62 children aged 17 were sent in by US forces, according to the report.
In its detailed study covering five continents since 2001, it warns that while wars ending in Afghanistan, Angola and Sierra Leone led to the demobilisation of 40,000 children, over 25,000 were drawn into conflicts in Ivory Coast and Sudan alone.
In the Democratic Republic of Congo, armed groups sexually abused and raped girls and forced children to kill their own relatives, the report said.
In Colombia, child soldiers of the FARC guerrilla group were ordered to execute other children for disciplinary offences.
Children have been used as informants, spies or messengers in hotspots such as Indonesia, Israel and Nepal.
"A world that does not allow children to fight wars is possible, but governments must show the political will and courage to make this happen by enforcing international laws," said Casey Kelso, head of the CSUCS.
The coalition is made up of human rights groups including Amnesty International and Human Rights watch and charities such as Save the Children and World Vision.
Children used as informants, spies and messengers
Captured child soldiers were tortured and killed
Child soldiers ordered to execute other children or relatives
Rachel Brett, of the Quaker United Nations Office in Geneva, a member of the coalition, told BBC News that child soldier recruiters were already facing prosecution in conflicts including Uganda, the DR Congo and Sierra Leone.
"The first successful prosecution for using children in this way will have a huge impact," she said. "If these recruiters know they will be caught, it will force them to change their behaviour."
Ms Brett said governments and rebel groups were "remarkably sensitive" about how accusations of using child soldiers could harm their credibility.
"If governments are being named by the UN Security Council, then I think they will take that seriously," she added.
The CSUCS wants a ban on recruiting under 18s into the armed forces but most child soldiers are members of rebel groups, or government-backed militias.
Many are forced to take up arms, others volunteer to fight to take revenge, or to make a living.