A new video released by Islamist terror group Boko Haram appears to show some of the 284 school girls kidnapped from their school at gunpoint last month in northern Nigeria.

A clip from the video released by Boko Haram via AFP news agency

The chilling footage, released to French news agency AFP, shows Boko Haram leader Abubakar Shekau speaking to camera before panning to what he says is a group of some of the girls abducted from their dormitories in Chibok, in Nigeria's Borno state, on April 14.

In the 17-minute video, Shekau claims the girls have converted to Islam and vows to hold them until all imprisoned militants from his group had been released by the Nigerian government.

Three girls are seen speaking to camera, one of whom claims she is Muslim and the other two who say they were Christian and have now converted to Islam.

Boko Haram leader Abubakar Shekau in the latest video released by the group

"These girls, these girls you occupy yourselves with... we have indeed liberated them. These girls have become Muslims," Shekau says.

"We will never release them [the girls] until after you release our brethren. Here I mean those girls who have not submitted [converted to Islam]."

The larger group of girls, all wearing full veils, are then seen to recite the first chapter of the Muslim holy book, the Qu'ran, together. They appear relatively calm but their smaller number (around 100, instead of the 284 kidnap toll) seems to confirm reports that they have been divided up into smaller groups.

There's no confirmation on where this latest video was recorded or when.

One of the abducted girls speak to camera

Shekau had previously said he would sell the girls, who are believed to be located somewhere in the vast and lawless Sembisa Forest region of northeast Nigeria.

"I will sell them in the market, by Allah. I will sell them off and marry them off. There is a market for selling humans," he said, in an earlier video where he admitted kidnapping the group.

BBC correspondent John Simpson, who's based in northern Nigeria, says this latest video may be a sign that Boko Haram are willing to engage in negotiation over the group.

Malala Yousafzai has been a vocal campaigner from the outset of the crisis

The girls' abduction has triggered an international outcry over the past month, with the UK and the US sending specialist assistance to the region to help with the search. Israel is also contributing a team of counterterrorism experts to help with the crisis, it was confirmed at the weekend.

Michelle Obama took her husband's place in the U.S. weekly address this Saturday to express her outrage over the situation.

"This unconscionable act was committed by a terrorist group determined to keep these girls from getting an education – grown men attempting to snuff out the aspirations of young girls," she said. "I want you to know that Barack has directed our government to do everything possible to support the Nigerian government's efforts to find these girls and bring them home. In these girls, Barack and I see our own daughters. We see their hopes, their dreams, and we can only imagine the anguish their parents are feeling right now."

The First Lady also lent her voice to a #BringBackOurGirls viral campaign on Twitter and Instagram, alongside the likes of Naomi Campbell, Bradley Cooper and education activist Malala Yousafzai.

UNHCR special envoy Angelina Jolie described the abductions as an act of "unthinkable cruelty and evil".

Michelle Obama urges an end to the mass abduction

Meanwhile the Nigerian government has come under fire over its lack of action in the crisis, with military officials struggling to penetrate the Sembisa Forest area of northeast Nigeria.

Last week, police officials offered a 50m naira (£177,000 or $300,000) reward on information leading to the location of the kidnapped group.

A statement from the Nigerian police high command promised the money to anyone who "volunteers credible information that will lead to the location and rescue of the female students."

As well as the 284 girls held from the attack on 14 April, Boko Harem has also abducted a further eight girls, aged between eight and 15, in an overnight raid on a village last week.

This brings the total held captive to 284, with a further 50 girls managing to escape as the armed rebels made their way through villages away from the school in Chibok, killing people and burning down buildings en-route.

A host of Hollywood men, including Sean Penn, Ashton Kutcher, Justin Timberlake and Bradley Cooper, add their voices to the campaign to free the girls

"I thought it was the end of my life," Deborah Sanya, one of the survivors who managed to escape Boko Haram, told the New Yorker. "There were many, many of them." She described how she and some of her friends fled the group, after they witnessed their abductors shooting their guns in the air in a remote region of the bush.

"I am pained that others could not summon the courage to run away with me," another survivor, Sarah Lawan, told the Associated Press. "Now I cry each time I come across their parents and see how they weep when they see me."

As the days go by with no sign of their daughters, the girls' family members are becoming increasingly fraught.

"We don’t know where they are up until now, and we have not heard anything from the government," Ishaya Sanya, one of the victim's fathers commented to the New Yorker. "Every house in Chibok has been affected by the kidnapping."

The kidnapped girls are apparently shown in a new video from Boko Haram

Boko Haram - whose name means "Western education is forbidden" - began its terror campaign in Nigeria in 2009 and its actions have resulted in the loss of over 4000 lives in the past four years. At least 75 people were killed in a car bombing in the capital, Abuja, last month, and a further 50 pupils were massacred at a school in Yobe state in February. It's also thought to be behind a massacre of 300 people in a market in Gamboru Ngala, a town close to the border with Cameroon in Nigeria's lawless northeast region, last week.

The group claims to be fighting for an Islamic state in northern Nigeria, with strict adherence to Sharia law.

Words: Anna Brech