Isaac Rebecca, one of the girls who escaped from the Boko Haram camp, speaks during a protest in Abuja Reuters

After being kidnapped and abused, many of the hundreds of girls snatched in Nigeria by Boko Haram militants could be facing the end of their lives as suicide bombers.

Boko Haram has a reputation for using children as bombers because they do not arouse the suspicion of security forces. Girls in particular do not attract attention and may more easily hide bombs in loose-fitting clothing.

The use of girls as bombers appears to be intensifying. In the latest attack earlier in May, a girl believed to be 12 blew herself up in a busy market near a bus station in Damaturu, killing at least seven people and injuring dozens.

Three female suicide bombers also killed nine security members near the Giwa military barracks in Maiduguri, the capital of Borno state. Earlier in 2015, yet another female bomber killed at least 10 people at the Damaturu bus station, reports Reuters.

Zannah Mustapha, deputy governor of Borno state, said in May that Boko Haram has outfitted hundreds of girls and women to become suicide bombers and target Maiduguri in a push to take the city. Most of the females used in suicide bombings appear to be adolescents or younger.

"Militants feel it is easier to intimidate and brainwash young girls than adult women. Besides, these girls come cheap, and most of them are extremely loyal," Yusuf Mohammed, who works with young people affected by trauma in Maiduguri, told the Daily Beast.

The use of girls as bombers began not long after more than 220 girls were kidnapped from their school in Chibok in 2014, the assault that launched the #BringBackOurGirls campaign that has so far had no success.

The age of the bombers hints some of the victims could be Chibok girls, though there is no clear evidence. Many of the girls could have become indoctrinated into their captors' beliefs, notes the Daily Beast.

The suspected bomber in a July 2014 attack at a university in Kano bore a resemblance to one of the abducted schoolgirls.

Local sources say when women are abducted by the militants, the "young and smart" girls are separated from the older ones and trained on how to handle heavy weapons or carry out suicide attacks. Soldiers said they were shocked when kidnapped women opened fire on troops who had come to rescue them in Sambisa forest.

A 13-year-old girl who was rescued from a Boko Haram camp in Bosso said: "They repeatedly told us that the best jihad is the one in which your horse is slain and your blood is spilled."