According to Aid to the Church in Need, poverty-stricken youngsters are being lured off the streets of the Democratic Republic of Congo and taken to remote camps where they are being brutalised and indoctrinated by Islamist militia.
Boys, spread across at least three camps in the Ruwenzori Mountains of eastern DRC, were sighted in camouflage kit doing military exercises watched over by soldiers with guns.
The reports describe up to 60 girls huddled together in the camps wearing burkhas, being prepared for marriage to Islamic fighters.
Maria Lozano, ACN vice-director of communications, said: "We have been given access to a variety of materials that shows the nature of these camps.
"The reports show soldiers wielding rifles, watching over the children aged nine to 15 in military outfits carrying out military exercises.
"The images we have seen are very disturbing."
One of the camps is in Medina, about 50 miles from Beni city in the region of which nearly 500 people have been killed in a string of massacres which have taken place since October.
Ms Lozano said: "We are very concerned for the children as they have been lured off the streets with the promise of an escape from poverty.
"Some of the children are orphans but others have left their families after being deceived by recruiters who build up their hopes by offering them the chance to study in the Middle East, Europe or Canada.
"The information we have is that the girls are being forced into marriages in which they will be treated as sex slaves."
The sudden emergence of the jihadist camps is being linked by the ACN sources to UN peace keeping forces with concerns that they are complicit in the camps and that they are intentionally failing to take action against them.
It is alleged that some members of the Mission of the United Nations Organisation for the Stabilization of DR Congo are fundamentalist Muslims from Pakistan who in their spare time in the African country are setting up Quranic schools and working on mosque construction sites.
The ACN contacts have claimed that the mosques have been built in areas where virtually no Muslims were living.
Ms Lozano said: "People don't feel protected by the UN soldiers; the information we have received suggests that they are supporting the jihadist camps or at least they are not taking action against the indoctrination of children and the barbaric treatment of them."
According to the 2014 Journal of International Organisations Studies, 28 of the 44 mosques (63 percent) in the Medina region of DRC were erected between 2005 and 2012.
Reports have stated that within a few years Muslim numbers in eastern DRC have risen from 1 percent to 10 percent.
The Catholic bishops of the ecclesiastical province of Bukavu, in eastern DRC, sent an open letter last May to the country's President, the UN and international leaders denouncing an upsurge of jihadist fundamentalism in a region traditionally dominated by Christianity and where there have been very few Muslims until now.
Ms Lozano stated: "It has already been one month since the Bishops' Conference sent their urgent appeal to the President of the Democratic Republic of the Congo and other leaders but nobody has acted."
