Boko Haram has released 82 schoolgirls from a group of 276 they abducted in north-eastern Nigeria three years ago, President Muhammadu Buhari’s office says.
The girls were handed over in exchange for Boko Haram suspects after negotiations.
They will be received by President Muhammadu Buhari in Abuja on May 7, a statement said.
The abduction of the so-called “Chibok girls” triggered a global outcry and sparked a huge social media campaign.
Before the latest release, about 195 of the girls were still missing.
The number of Boko Haram suspects released by authorities remains undisclosed.
Christian pastor Enoch Mark, whose two daughters were among those kidnapped, told AFP: “This is good news to us. We have been waiting for this day. We hope the remaining girls will soon be released.”
It was unclear whether his daughters had been freed.
A statement from a spokesman for President Muhammadu Buhari said he was deeply grateful to “security agencies, the military, the Government of Switzerland, the International Committee of the Red Cross, and local and international NGOs” for playing a role in the operation.
After the Government Girls Secondary School in Chibok, Borno state, was raided in April 2014, more than 50 girls quickly escaped and Boko Haram then freed another 21 in October 2016, after negotiations with the Red Cross.
Last month, President Muhammadu Buhari said the Nigerian government remained “in constant touch through negotiations, through local intelligence to secure the release of the remaining girls and other abducted persons unharmed”.
Many of the Chibok girls were Christian, but were encouraged to convert to Islam and to marry their kidnappers during their time in captivity.
Michelle Obama has said the mass kidnap of Nigerian schoolgirls is part of a wider pattern of threats and intimidation facing girls around the world who pursue an education.
The first lady said she and President Barack Obama were “outraged and heartbroken” over the abduction on April 14 of more than 200 girls from their school.
Michelle Obama was speaking instead of her husband in the weekly presidential address.
Michelle Obama was speaking instead of her husband in the weekly presidential address (photo White House)
The Islamist militant group Boko Haram has claimed the abductions.
Michelle Obama, who was speaking ahead of Mother’s Day in the US on Sunday, said the girls reminded her and her husband of their own daughters.
“What happened in Nigeria was not an isolated incident. It’s a story we see every day as girls around the world risk their lives to pursue their ambitions,” she said.
Michelle Obama cited the Pakistani schoolgirl and campaigner Malala Yousafzai, who was shot and wounded by the Taliban for speaking out for girls’ education.
“The courage and hope embodied by Malala and girls like her around the world should serve as a call to action,” she said.
It is unusual for a US first lady to make outspoken foreign policy remarks, but Michelle Obama has campaigned for the girls’ release.
Michelle Obama has often appeared alongside her husband during the weekly address, which is broadcast on radio with a video version available online. This is the first time she has delivered the speech alone.
Earlier this week, Michelle Obama tweeted a picture of herself in the White House holding a sign with the message “#BringBackOurGirls”.
The UN Security Council expressed outrage over the abductions, saying it would consider “appropriate measures” against Boko Haram. The US is seeking to have UN sanctions imposed on the group.
Michelle Obama is to deliver Barack Obama’s weekly presidential address to condemn last month’s abduction of Nigerian girls.
First ladies normally refrain from outspoken foreign policy remarks, but Michelle Obama has been a vocal campaigner for the release of more than 200 girls.
Fifty-three of the schoolgirls escaped soon after being seized in Chibok on April 14 but many more remain captive.
Islamist militant group Boko Haram claimed responsibility for the attack.
Michelle Obama is to deliver Barack Obama’s weekly presidential address to condemn last month’s abduction of Nigerian girls
The United Nations Security Council expressed outrage over the abductions in north-eastern Borno state, and demanded the immediate release of the students.
It said it would consider “appropriate measures” against Boko Haram. The US is seeking to have UN sanctions imposed on the group.
Michelle Obama is due to make the address ahead of Mother’s Day, which the US marks on Sunday.
“As the mother of two young daughters, Mrs. Obama is taking up the opportunity to express outrage and heartbreak the president and she share over the kidnapping,” White House deputy spokesman Eric Schultz said.
“The first lady hopes that the courage of these young girls serves as an inspiration… and a call to action for people around the world to fight to ensure that every girl receives the education that is their birthright,” he added.
Michelle Obama has often appeared alongside her husband during the weekly address, which is broadcast on radio with a video version available online. This is the first time she will deliver the speech alone.
Earlier this week, she tweeted a picture of herself in the White House holding a sign with the message “#BringBackOurGirls”.
President Barack Obama has described the kidnapping as “heartbreaking” and “outrageous”.
A small number of US and British experts have now started arriving in Nigeria to assist the government’s rescue efforts.
A senior US official said Washington was also considering a Nigerian request for surveillance aircraft.
But analysts have pointed out the difficulty of using aerial reconnaissance in the region’s rugged forests.
Nigerian President Goodluck Jonathan said on Friday he believed the schoolgirls were still in his country and had not been moved to neighboring Cameroon.
Boko Haram has admitted capturing the girls, saying they should not have been in school and should get married instead.