Twenty-one of the Chibok schoolgirls kidnapped by Boko Haram more than two years ago have been freed in a swap for detained leaders of the Islamic extremist group.
It's the first release since nearly 300 girls were taken captive in a case that provoked international outrage.
The freed girls, some carrying babies, were released before dawn and placed in the custody of the Department of State Services, Nigeria's secret intelligence agency.
In photos released by the government, the former captives, most now young women, appeared gaunt and exhausted.
The government ``wants the girls to have some rest,'' said presidential spokesman Garba Shehu, adding that ``all of them are very tired.''
Some 197 captives remain missing, though some reportedly have died.
``We are extremely delighted and grateful,'' said the Bring Back Our Girls movement, which campaigned in Nigeria and internationally for the release of the girls, most of whom were teenagers when they were seized in April 2014 from their school in the northeastern town of Chibok.
``We thank the federal government and, like Oliver Twist, we ask for more,'' said Hauwa Biu, an activist in Maiduguri, the capital of northeastern Borno state and the birthplace of Boko Haram.
The release was negotiated between the government and Boko Haram, with the International Committee of the Red Cross and the Swiss government acting as intermediaries, Shehu said. He said negotiations would continue for the release of the other students.
Many of the girls freed on Thursday were carrying babies, said an aid worker who saw them in Maiduguri, where they were taken by helicopter after their release, before being flown to the capital, Abuja.
He spoke on condition of anonymity because he was not authorised to speak to the media.
Many Boko Haram captives recently freed by military action have been shunned by their communities because they came home pregnant or with babies from the fighters.
Four detained Boko Haram leaders were released on Wednesday night in Banki, a town on Nigeria's northeast border with Cameroon, said a military officer familiar with the talks.
Just hours later, the girls were released in Banki, said the officer, who spoke on condition of anonymity because he was not authorised to speak to journalists.
But Information Minister Lai Mohammed insisted there was no swap, just ``a release, the product of painstaking negotiations and trust on both sides.''
The abduction of 276 schoolgirls from their school in Chibok and the government's failure to quickly free them caused an international outcry 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 some 197 remain missing.
