A United Nations proposal to keep children out of war zones could see a bar on young people joining the British armed forces - and scupper plans for a new military college.
The Department for International Development, headed by Clare Short, says it is considering the move which would ban 16 and 17-year-olds from the British military.
The proposal aims to stop child soldiers being used in countries such as Angola and Uganda, where children as young as five are press- ganged into fighting.
But it has been rejected by the British Army which says young recruits are essential.
Michael Devlin, a spokesman for the Army, said he did not think that Britain would sign up.
"There is no change of policy envisaged for the military," he said. "The armed forces require about 25,000 people each year, 15,000 for the Army alone. " He said the Army was to open a new military college for young people later this year.
There are 1,700 16-year-olds and 2,800 17-year-olds in the Army, Navy and Air Force combined, out of a total complement of 210,800, and their employment has until now attracted little controversy.
A spokeswoman for the Department of International Development said Ms Short had not made a call for under-18s to be banned from the British armed forces, but said there was considerable concern over the use of child soldiers in developing countries.
She said a UN proposal to bar their recruitment to the military was being considered. The Department of Health, which is responsible for children, would make the final decision. The Ministry of Defence would also be consulted.
Mr Devlin said that the new military college offering 42-week courses to 16-year-olds would be opening in September in order to make the military more attractive to school-leavers.
"It's important that we have access to the individuals leaving school because we're in competition with civilian firms on the job front. It's much more difficult to compete for adult recruits," he said.
The Army Foundation College, which opens in Harrogate in September, will play a major role in attracting school-leavers and preparing them for front-line roles, he said.
In the first year 600 16-year-olds, both boys and girls, would be admitted, rising to 1,300 within a few years.
There will be no academic requirements for admission to the 42-week course beyond basic literacy and numeracy tests, and students, who will be required to dress in uniform, will follow a rigorous programme of vocational training, including information technology skills, and physical exercise.
Mr Devlin argued that the Army was an ideal place for many school-leavers to build a career.
"If you compare the job of a 16-year-old stacking supermarket shelves with the vocational training at the Army technical college, I think the benefits speak for themselves," said Mr Devlin. "We aim to put back into society individuals with a sense of self-discipline and teamwork and the concept of service before self.
"I think a lot of individuals who have been denied any form of male role-models, either because of family circumstances or because of the composition of the teachers in their school, find that the Army gives them the first form of male role models they've had."