A European conference in Berlin will criticise the UK as being one of the worst offenders for recruiting what it calls "child soldiers".
The Coalition to Stop the Use of Child Soldiers - an international coalition of pressure groups - wants to raise the minimum age for recruiting and participating in armed conflict to 18.
The problem of child soldiers is mostly associated with Africa where young children, sometimes under 10, are regularly used by irregular forces in the continent's civil wars.
It has been estimated that in the past decade, wars have killed two million children and maimed six million, as well as creating 12 million refugees.
The UK's armed forces recruit school leavers from the age of 16, and they can be used on operations from 17 - the limit under current international conventions.
Limit rejected
The use of child soldiers is one of the most horrifying aspects of many modern civil wars, especially in the anarchic conflicts in Africa, but this conference says the problem extends to Europe, and particularly criticises Britain for using under-18s on the frontline.
In August the United Nations Security Council called on all countries to do more to protect children in war zones. It unanimously adopted a resolution condemning the recruitment of child soldiers and the killing and abuse of children in conflicts.
At the time the council was told that 300,000 children were currently serving as soldiers, guerrilla fighters or in support roles in more than 30 countries, including Sudan, Colombia, Angola, Sri Lanka and Afghanistan.
Campaigners also back a UN optional protocol to raise the minimum age to 18. They say younger people in the armed forces are too vulnerable.
Comparison 'absurd'
But the UK and many other nations, including America, reject the proposed limit.
Britain says like any other employer it should be able to recruit people straight out of school, and they are all volunteers for a long-term career.
Sixteen-year-olds also need parental permission to join, and will be well past their 17th birthday before joining the frontline
While publicly diplomatic, the services privately see any comparison between Britain's policy and the situation in places like Sierra Leone as absurd, and also a diversion from the real issue.
Country profiles
From killing fields to the field of dreams
(12 Sep 99 | Scotland)
UN move to protect children from war
(26 Aug 99 | World)
UN fears for Afghan child soldiers
(20 Aug 99 | South Asia)
The child victims of war
(25 Jun 99 | Africa)
Sri Lanka's children of war
(22 Jun 98 | South Asia)
Coalition to Stop the Use of Child Soldiers
UN special report on children and armed conflict
UN resolution on children in war zones
The British Army
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