05/05/2014 12:21 BST | Updated 05/05/2014 13:59 BST

Boko Haram Leader Says He Will 'Sell' Abducted Nigerian Schoolgirls In Chilling Video

Boko Haram will "sell your girls in the market", the terrorist leader has vowed in a chilling video message to parents of the kidnapped Nigerian schoolgirls.

Abubakar Shekau, the leader of the Nigerian Islamist group notorious for targeting schools, claimed responsibility for the abduction of hundreds of girls aged 16 to 18 from their Borno state school in a video message released by Agence France Press.

It is three weeks since the girls were abducted and Boko Haram has threatened to 'sell' them

"I abducted your girls. I will sell them in the market, by Allah," Shekau said, according to the news agency's translation. "We are holding people [as] slaves."

The girls should be married, not in school, he continued, according to the BBC.

"God instructed me to sell them, they are his properties and I will carry out his instructions."

Authorities searching for the missing girls say dozens have escaped from their captors but 276 are still missing. They were taken three weeks ago from their school in Chibo.

Last week, senior community leader Dr Pogu Bitrus told Channel 4 News that he believed many of the girls, who were mainly Christian, were compelled to convert to Islam and "forcibly married off with a bride price of just 2,000 Naira [less than £10]." He did not cite his sources.

But a different source, involved in the hostage negotiations, told Channel 4 News that he believes the girls will be returned safely for a ransom. "It would not be hard to engineer a deal. It looks like they want to release them," he said.

As anger swells in Nigeria over the handling of the case, and protest marches take place across the nation, police arrested the leader of a group that called on authorities to do more to find the kidnapped girls.

Reuters reported that Naomi Mutah Nyadar had been detained, suspected of falsely claiming that one of the abducted girls was her daughter.

But local reports suggest the arrest was connected with a meeting with Nigeria's First Lady Patience Jonathan, who had felt slighted that the mothers of the girls did not come to meet her, and were instead represented by Mutah Nyadar, who is from the girls' local Chibok community.

AP quoted community leader, Saratu Angus Ndirpaya, as saying that Jonathan accused the activists of fabricating the abductions in order to smear her husband's government.