ABUJA • Nigeria has denied reports that the government had swopped Boko Haram fighters for the release this week of 21 schoolgirls kidnapped by the militant group in 2014.

"Please note that this is not a swop," said Information Minister Lai Mohammed on Thursday, when the government announced the girls' release.

"It is a release, the product of painstaking negotiations and trust on both sides. We see this as a credible first step in the eventual release of all the Chibok girls in captivity."

He said he was unaware if any ransom had been paid.

Around 270 girls were taken from their school in Chibok in April 2014 in the remote north-eastern Borno state, where Boko Haram has waged a seven-year insurgency aimed at creating an Islamic state, killing thousands and displacing more than two million people.

Soon after the girls were kidnapped, an international campaign began urging the Nigerian government to do more to secure their release, using the hashtag #BringBackOurGirls and drawing support from American First Lady Michelle Obama and others.

The 21 girls were freed after the Red Cross and the Swiss government brokered a deal with the group, officials said on Thursday.

Switzerland "facilitated contacts between Nigerian representatives and intermediaries of Boko Haram" after a request from Abuja, a Swiss government spokesman said.

"We have nothing to add," she said, when asked if there had been a prisoner swop.

The girls were released around 5.30am on Thursday, the government said.

In addition to the 21 girls, a 20-month-old boy born to one of them in captivity was released.

At a news conference in the capital Abuja, the girls sat in rows in a room packed with government ministers, officials and camera-wielding journalists.

Wearing colourful dresses, the girls listened to Vice-President Yemi Osinbajo speak from behind a table, flanked by his ministers.

"We can imagine what they've gone through," he said. "So much needs to be done to get them back to living a normal life after so much trauma in captivity."

Mr Osinbajo described the girls as being in "reasonably good health considering the circumstances they've been held in".

He said that they would stay in a medical facility "for some time, until we're reasonably satisfied of their health condition".

As for the other girls held by Boko Haram, Mr Osinbajo suggested that "in the next few days, the next few months, we should be able to bring in more of these girls, along the same lines, using exactly the same negotiations".

Relatives of the girls rejoiced, even before they knew whether their kin were among the freed. Mr Lawan Zanna, the father of Aisha Zanna, one of the abducted girls, said by telephone that he hoped his daughter had been freed. All of the parents are "very happy to hear that they have released our daughters", he said. "All are our daughters."

Boko Haram controlled a swathe of land around the size of Belgium at the start of last year, but Nigeria's army, aided by troops from neighbouring countries, has recaptured most of the territory.

The group still stages suicide bombings in the north-east, as well as in neighbouring Niger and Cameroon.

Boko Haram published a video in August apparently showing recent footage of dozens of the kidnapped girls and said some had been killed in air strikes.

REUTERS, NY TIMES