KINSHASA, Congo — Boys and girls are being recruited in record numbers to act as soldiers, spies and sex slaves in Congo and children have been spotted marching in formation in the war-wracked east of the country over the past week, international charity Save the Children said Monday.

Fighting in lawless eastern Congo has escalated dramatically since August, as rival rebel militias clash over the forested territory, the London-based charity said. Those children who have managed to escape have told the aid organization they were held captive in small holes in the ground.

"The situation for children in eastern Democratic Republic of Congo is catastrophic. Fighters from all sides are using children as frontline fodder," said Hussein Mursal, Congo director for Save the Children.

Schools have been targeted as "rich recruitment ground," the charity said.

The group which has provided refuge to 800 child fighters this year said because the conflict continues to escalate, it has not been able to return the children to their homes.

"The risk of re-recruitment and physical danger from the war are so high," the group said.

The United Nations said earlier this month that about 8,500 former child soldiers have left armed groups and returned to their families since 2004, but some of the same children have been rounded up and forced to fight again.

An estimated 800,000 people have fled their homes this year in eastern Congo, which shares a border with Rwanda. The area has been wracked by violence for years, despite the end of a five-year war in 2002.

The continued conflict is fueled, in part, by the region's proximity to Rwanda. Rebels accused of orchestrating Rwanda's 1994 genocide were expelled from the country and have operated from eastern Congo.

One of those groups, the Democratic Front for the Liberation of Rwanda, is among the most active recruiters of child soldiers, according to a recent United Nations report. Its commanders are accused of organizing the killing of 500,000 people during the Rwandan slaughter 13 years ago.

The charity has been actively negotiating with the rebels for the release of the children. Those who are released are housed by aid workers in a safe place, where they are provided counseling services.