The organisation, Waging Peace, has filmed testimony in refugee camps in eastern Chad, describing how children, mostly boys between nine and 15, have been forcibly taken from their families by camp leaders, who are then trafficking them to militias.
Today's report singles out the Darfur rebel group fighting the Khartoum government, the Justice and Equality Movement, as the main offender. But it says a variety of groups, including the Chadian army and opposing rebels, are also involved.
"This recruitment is taking place every day, in full view of the CNAR [Chadian government body in charge of refugees] and Chadian armed forces, who turn a blind eye to what is going on, and despite the presence of EU troops," the report says.
The EU force in Chad, Eufor, will be made up of more than 4,000 troops, half of them French, and is due to be fully deployed by next month. Waging Peace is calling on the force, led by an Irish lieutenant general, Patrick Nash, to protect the refugee camps from the militias and to help stop the trafficking.
Louise Roland-Gosselin, the head of Waging Peace, said: "The deployment of the EU force means there is supposed to be security in the camps, but it hasn't come true. People feel deceived."
Roland-Gosselin said it was impossible to know how many children were being abducted, but the UN estimated last year that between 7,000 and 10,000 child soldiers had been forcibly recruited in Chad, where more than 250,000 refugees from Darfur are in camps. She said the problem had worsened since then, despite attempts by UN agencies and aid groups to negotiate an end to trafficking.
One of the refugee leaders opposed to the practice told Waging Peace: "Now it's worse, it's not only aggressive but worse ... They are selling anybody, you know, the boys from nine to 15 in the camp they are just selling them."
He accused other senior men in the camp of being involved in the trade.
Another refugee leader told Waging Peace: "We are very concerned about the future of our children who have survived the killing in Darfur. We want them to study and have a future. We don't want them to join the fighters and become useless."
Serge Male, the head of the UN's refugee agency UNHCR in Chad, said: "For a good while we have been trying to call attention to child recruitment in the camps, both forced and voluntary. We definitely condemn this and we are dealing with the Chadian authorities, the UN agencies and all the parties who have something to do with this."
The report says that, in part because of their role in kidnapping, the Justice and Equality Movement rebels are losing support among the Darfuri refugees in the camp. Efforts to negotiate a peace deal between the rebel groups and the Khartoum government have faltered because the rebel side has splintered and the government has pursued an aerial bombing campaign against rebel strongholds.
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