Sara Morales is in her early 20s, but already, she says, she's been to hell and back. The Colombian woman who lives in Bogota says she was forcibly recruited by the main guerrilla group in her country when she was just a young girl.

"When I was only 11 years-old I was raped by FARC guerrillas and for 11 years I was abused and exploited by them," Morales said.

FARC is a Spanish acronym for the Revolutionary Armed Forces of Colombia, a leftist guerrilla group that has been at war with the Colombian government for about five decades.

Stories about children kidnapped or forcibly recruited by guerrilla groups came back into focus in 2006 when the Colombian government released a video confiscated during an army raid. The video showed squads of young kids being trained as guerrilla warriors in the middle of the jungle.

A recent study suggests that in the years after the video was released, armed groups, including paramilitaries, guerrillas and drug cartels, have not only continued recruiting children, but have increased the number of minors in their ranks in a dramatic way.

The study called "Like Lambs Among Wolves" was authored by Natalia Springer, the dean of the law school at Universidad Jorge Tadeo Lozano in Bogota, Colombia. Springer, who's also a political analyst and a human rights activist, has found that in the last four years, 18,000 children have been forced to join guerrilla groups and paramilitaries in Colombia.

"We actually have a humanitarian emergency in Colombia regarding the recruitment of children," Springer said. According to Springer, some of the minors taken away by armed groups are kidnapped, but others, especially those who live in remote, marginalized, and impoverished areas of Colombia, are lured by the prospect of food and shelter.

The findings of her study are chilling. Springer says she found 69 percent of those captured are 14 years of age or younger, some as young as eight. Ninety-eight percent reported they were abused or witnessed atrocities.

Springer also says that guerrilla groups recruit children to do "their dirty work" which includes extremely dangerous activities in which their lives are constantly at risk. "They're installing land mines, they're transporting explosives, they're kidnapping, they're involved in all of the activities that the adults are doing," Springer said.

Springer says her team noticed what she calls an alarming new trend. Whereas in the past the vast majority of the children captured by the armed groups were boys, the percentage of kidnapped girls has dramatically increased to 43 percent. In addition to combat activities, Springer says these girls are subjected to sexual servitude.

"For them it's a duty to sexually serve their commanders so by serving their commanders they identify a number of activities that for them were humiliating and difficult to accept," Springer said.

The Colombian government does not dispute that children are being recruited in large numbers, but questions the study's statistics.

Diego Molano Aponte, who's in charge of the Colombian Institute for Family Welfare, says he shares Springer's concern about the situation, but believes some data gathered for the study may be inaccurate.

"We, the government, have some doubts regarding the total number of 18,000 kids. We believe that their sources should be double-checked, because the statistic should be less than that. But in any case, it's continues to be a problem," Molano said.

Springer notes most of the children recruited are essentially illiterate - and indigenous Colombians are especially vulnerable. Among those who get recruited by the violent, armed groups, extreme poverty is the common denominator.

Sara Morales, the survivor, says she often thinks about the children who didn't make it. "We were a group of 300 children and only 12 of us were lucky enough to survive. We were 300 children who were subjected to all kinds of abuses by the guerrilla," Morales said.

The rest, Morales says, succumbed to disease or died in combat. Many others were forever silenced by land mines or their own commanders.