A group of Chibok schoolgirls kidnapped by Boko Haram in Nigeria more than two years ago has been freed in a swap for detained leaders of the Islamic extremist group.
Some 197 girls remain captive after the release of 21, though it is not known how many of the original group may have died.
The freed girls, the first to be released as a result of government action, are in the custody of the Department of State Services, Nigeria’s secret intelligence agency, according to presidential spokesman Garba Shehu.
Their release was negotiated between the government and Boko Haram in talks brokered by the International Committee of the Red Cross and the Swiss government, he said.
Negotiations will continue for the release of the other students, he said.
A military officer familiar with the talks said four detained Boko Haram leaders were released in Banki, a town on the north-east border with Cameroon.
The girls were flown by helicopter to Maiduguri, the northeastern capital of Borno state and birthplace of Boko Haram, he said.
“We are extremely delighted and grateful,” the Bring Back Our Girls movement said.
The group, which has campaigned for the release of the students, said it awaits the names of the released girls.
“We thank the federal government and, like Oliver Twist, we ask for more,” said Professor Hauwa Biu, an activist in Maiduguri.
Negotiations last year failed when Boko Haram demanded a huge ransom for the girls’ freedom, according to a recently published authorised biography of President Muhammadu Buhari.
The abduction of 276 schoolgirls in April 2014 and the government’s failure to quickly free them has caused international outrage and brought Boko Haram, Nigeria’s home-grown Islamic extremist group, to the world’s attention.
Dozens of the girls escaped on their own, but most remain missing.
One of the girls, Amina Ali Nkeki, escaped in May on her own. She told her family that some of the kidnapped girls have died of illness and others, like her, have been married to fighters and are pregnant or have babies, her mother said.
Since then Ms Nkeki has been in the custody of the secret service where she is receiving medical care and trauma counselling, according to President Muhammadu Buhari’s government.
The government has been criticised for keeping her isolated. The Bring Back Our Girls group and Human Rights Watch have asked whether Ms Nkeki is a detainee of the government.