ABUJA (Reuters) - Jihadist group Boko Haram has freed 21 of more than 200 girls it kidnapped in April 2014 in the northern Nigerian town of Chibok, after mediation by Switzerland and the International Red Cross, officials said on Thursday.

Around 270 girls were taken from their school in Chibok in the remote northeastern Borno state, where Boko Haram has waged a seven-year insurgency aimed at creating an Islamic state, killing thousands and displacing more than 2 million people.

“I met them about an hour ago and I can confirm they are in good health,” Nigerian Vice President Yemi Osinbajo said after meeting the 21 released girls, who were brought from the northeastern city of Maiduguri to the capital Abuja.

Their release, a boost for the government of President Muhammadu Buhari, came after the Red Cross and the Swiss government brokered a deal with the group, officials said.

Dozens had escaped in the initial melee in 2014, but more than 200 girls are still missing. The kidnapping prompted outrage worldwide and the girls’ plight was publicized using a Twitter hashtag, #bringbackourgirls.

“In the next few days or months we will be able to negotiate the release of more of the girls,” Osinbajo told reporters.

A picture released by a presidency official showed one of the girls holding a baby when they met Osinbajo. Officials have accused Boko Haram of having married off the girls to its followers.

Information Minister Lai Mohammed denied reports that the government had swapped Boko Haram fighters for their release and said he was not aware if any ransom had been paid. He said a Nigerian army operation against Boko Haram would continue.

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

“We have nothing to add,” she said, when asked if it had been a prisoner swap.

In recent days, the Nigerian military has been carrying out a large-scale offensive in the Sambisa forest, a stronghold of Boko Haram, which last year pledged loyalty to the Islamic State militant group.

Boko Haram controlled a swathe of land around the size of Belgium at the start of 2015, but Nigeria’s army, aided by troops from neighboring countries, has recaptured most of the territory. The group still stages suicide bombings in the northeast, as well as in neighboring 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.

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The militant group has kidnapped hundreds of men, women and children but the kidnapping of the Chibok girls brought it worldwide attention.

Authorities said in May one of the missing girls had been found and Buhari promised to rescue the others.

In recent months he had said his government was prepared to negotiate with Boko Haram over their release.