Image copyright AFP Image caption Cameroonian security forces have joined a regional battle against Boko Haram militants 
 
 About 80 children rescued from a Boko Haram camp in Cameroon cannot remember their own names or origins, according to an aid official who visited them. 
 
 The children - aged between 5 and 18 - did not speak English, French or any local languages, says Christopher Fomunyoh, a director for the US-based National Democratic Institute (NDI). 
 
 The children were found at a camp in northern Cameroon in November. 
 
 Nigeria-based Boko Haram militants have extended their campaign into Cameroon. 
 
 The militants are fighting to establish an Islamic caliphate in north-eastern Nigeria. 
 
 They control several towns and villages in the region and recently pledged allegiance to Islamic State (IS) militants, who have seized large areas of Syria and Iraq. 
 
 'Lost touch' 
 
 The children were rescued in Cameroon after security forces - acting on a tip-off - raided what was thought to have been a Koranic school. 
 
 Mr Fomunyoh told the BBC's Randy Joe Sa'ah in Yaounde that he had visited an orphanage that was helping rehabilitate the children. 
 
 He said the children had spent so long with their captors, being indoctrinated in jihadist ideology, that they had lost track of who they were. 
 
 "They've lost touch with their parents," he said. "They've lost touch with people in their villages, they're not able to articulate, to help trace their relationships, they can't even tell you what their names are." 
 
 Meanwhile, a suspected Boko Haram attack on Tuesday killed at least six people at a marketplace in the northern Nigerian town of Maiduguri. 
 
 The suicide bombing was reportedly carried out by a middle-aged woman. 
 
 Boko Haram at a glance 
 
 Founded in 2002, initially focused on opposing Western-style education - Boko Haram means "Western education is forbidden" in the Hausa language 
 
 Launched military operations in 2009 to create Islamic state 
 
 Thousands killed, mostly in north-eastern Nigeria - has also attacked police and UN headquarters in capital, Abuja 
 
 Abducted hundreds, including at least 200 schoolgirls 
 
 Controls several north-eastern towns 
 
 Launched attacks on neighbouring states 
 
 Boko Haram pledge to IS raises stakes 
 
 Why is Boko Haram so strong? 
 
 Can regional force beat Islamists? 
 
 IS shaping Boko Haram media ||||| Breaking News Emails Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings. 
 
 / Updated 
 
 Three suicide bombings by girls aged as young as 10 suggest that Nigeria's Boko Haram has employed a new tactic of forcing abducted children to blow themselves up, according to experts. 
 
 The Islamist sect has been carrying out almost daily killings and kidnappings across northeast Nigeria in a campaign of violence now in its sixth year. Deadly attacks on Saturday and Sunday were carried out by three young female suicide bombers. 
 
 These came just days after a week-long killing spree by Boko Haram, in which the group torched at least 10 towns leaving around 2,000 people unaccounted for. Secretary of State John Kerry on Thursday called the attack "a crime against humanity." 
 
 It is not clear if the girls were coerced or were even aware they were strapped with explosives, which may have been detonated remotely. But experts say that Boko Haram appears to be using the children it kidnaps — such as the 276 Chibok girls who sparked the #BringBackOurGirls social media campaign — and using them as a readily available supply of suicide bombers. 
 
 "Using children to carry and detonate explosives is not a new tactic for Boko Haram but it is an intensification. Boko Haram has been abducting and conscripting children and young men and women for a long period for various purposes – they will be seen by the movement as expendable resources," said Elizabeth Donnelly, assistant head of the Africa program at London's Chatham House think tank. 
 
 Boko Haram roughly translates to "Western education is sinful." The group aims to create its own state based on strict Islamic law. 
 
 It has used female suicide bombers before, notably in a spate of attacks last July in central northern city of Kano. But Peter Pham, director of the Africa Center at the Atlantic Council, said the recent use of young girls represented a "ratcheting up" of the group's bombing campaign, "first to women and now to children." 
 
 "Young women who are abducted, it has been suggested that they might be used as wives. But it's certainly possible they could be used as bombers," he added. 
 
 "These girls just do not matter to them ... They are disposable bodies" 
 
 Increasing violence in Nigeria's northeast means reporting from the region has become next to impossible. Western journalists rarely get closer than the capital Abuja, 400 miles away. 
 
 But a reporter in the city of Maiduguri, the site of Saturday's bombing, characterized the use of girls by Boko Haram as "clearly a change in tactics." 
 
 "Getting the girls? Extremely simple," the journalist told NBC News, asking not to be named because of restrictions imposed by his employer. "Many towns and villages have been raided, and married women, young girls and even children below 10 have been abducted. These are the suicide bombers." 
 
 Eyewitnesses told Reuters news agency and local newspapers that the bomb in Maiduguri was strapped to a girl who appeared as young as 10 years old. Local Senator Ahmed Zanna told NBC News around 20 people were killed. The following day, two girls described as appearing the same age wore suicide vests that detonated in the town of Potiskum killing three people. 
 
 United Nations Secretary-General Ban Ki-moon condemned what he called a "depraved act."
– It was decidedly good news when a group of about 80 children was rescued from a Boko Haram camp in northern Cameroon in November—but the repercussions of their abduction remain painfully evident. An aid official who recently visited an orphanage that's helping the kids get reacclimated to a semblance of normal life tells the BBC that they don't speak "English, French, or any local languages" and that they can't even remember their own names. The militant group, which just this week officially pledged its allegiance to ISIS, has moved its campaign to set up an Islamic caliphate beyond Nigeria and started attacking border towns in neighboring Cameroon in recent months, CBS News notes. The children extricated from Boko Haram's grasp late last year are between the ages of 5 and 18, Christopher Fomunyoh, a director for the National Democratic Institute, tells the BBC—and they've sadly succumbed to Boko Haram's brainwashing for all things ideologically extremist, he adds. "They've lost touch with their parents, they've lost touch with people in their villages," he says. "They're not able to articulate, to help trace their relationships. They can't even tell you what their names are." (Recent suicide attacks in Nigeria appear to be Boko Haram assaults.)