Chibok Girl: Why Only 21 After Negotiation

Twenty-one of the more than 200 Nigerian girls kidnapped from a school in Chibok by Boko Haram fighters in 2014 have been released, according to Nigeria's presidency.

The release followed negotiations between Nigeria's government and Boko Haram brokered by Red Cross and Swiss government officials, a spokesman for the country's president said on Thursday.

"It is confirmed that 21 of the missing Chibok girls have been released and are in the custody of the Department of State Services," presidential spokesman Garba Shehu said in a statement. 

"The release of the girls ... is an outcome of negotiations between the administration and the Boko Haram brokered by the International Red Cross and the Swiss government," Shehu said.

The girls were exchanged for four Boko Haram prisoners in Banki in northeast Nigeria, AFP news agency said quoting a local source.

"For some time now there has been some negotiations between the Nigerian government and Boko Haram," according to a report from the Nigerian city of Kano.

"Remember a few months ago, the leader of the Boko Haram faction that seems to be holding the girls said that they can only release these girls if the Nigerian government releases some of its commanders being held in prison across Nigeria."

The identity of the girls has yet to be confirmed, said Aisha Yesufu, a Bring Back Our Girls campaigner.