Federal government is negotiating "seriously" for the release of more than 110 kidnapped Chibok schoolgirls still held by Boko Haram and will exchange more detained members of the extremist group for them if needed, an official said Thursday.

"We will not relent until all are back," the minister of women's affairs and social development, Aisha Alhassan, told reporters in the capital, Abuja.

The mass abduction of nearly 300 schoolgirls from a boarding school three years ago brought world attention to Boko Haram's deadly rampage in northern Nigeria. 

Thousands have been kidnapped or killed in the group's eight-year insurgency, with millions driven from their homes.

On Saturday, 82 of the Chibok schoolgirls were released. Nigeria's government exchanged them for five detained Boko Haram commanders, according to an official who spoke on condition of anonymity because he was not permitted to speak to reporters on the matter. Negotiations with the extremist group, mediated by the International Committee of the Red Cross and the Swiss government, also resulted in the October release of a first group of 21 Chibok girls.

Alhassan said the federal government had no regrets about exchanging Boko Haram commanders for the schoolgirls' release.

"We'll do it again if needed," she said in comments tweeted by the government.

Families in Chibok were meeting with community leaders to identify the newly freed schoolgirls from photos to determine if they will travel to the capital to meet them.

The young women were joining those released earlier in government care in Abuja, where they were undergoing medical screening that will take a couple of weeks, Alhassan said. 

Some must undergo surgery, she said.

The government has been caring for 24 previously released girls and four babies, Alhassan said. A small number of the schoolgirls managed to escape on their own.

The group of girls released in October were in "bad shape" and spent two months in medical care, the minister said.

Human rights groups have criticized the government for keeping them so long in the capital, far from their homes. Alhassan said they traveled to Chibok for Christmas but upon their return to the capital said they were scared to go back to their community.

The girls said they wanted to go back to school so a nine-month reintegration program was designed for them, the minister said. The newly released girls will join the program.

Parents of the freed Chibok schoolgirls "are free to visit them at any time. We will never prevent them from seeing their daughters," Alhassan said.

Some of the girls who escaped shortly after the mass kidnapping said some classmates had died from illness, and others were radicalized and didn't want to come home. Human rights advocates have said they fear some of the girls have been used by Boko Haram to carry out suicide bombings.

AP