Boko Haram has released dozens of schoolgirls kidnapped from their Nigerian village last month but kept hold of at least one because she is a Christian and refused to recant her faith.

Brandishing black and white flags and wearing military outfits and balaclavas members of the jihadist group drove into the centre of Dapchi village and returned most of the girls they had abducted on February 19.

Government officials said that at least 104 of the 110 girls who had been kidnapped had been returned but the total number freed is still unclear.

However Amnesty International suggests four are still being held including one girl thought by US officials to be a Christian. Her fellow captives told their families she was not released because she refused to convert, according to the New York Times.

The Nigerian government denied any ransoms were paid after they were accused of being slow to respond following the abductions, where Boko Haram members pretended to be government troops and herded the girls into trucks.

There are also reports in local media that around five of the captives died because of overcrowded conditions in the trucks.

'Dapchi is full of joy,' said Mohammed Mdada, who saw the girls being taken, according to the Guardian. He said the militants apologised to some of the girls' parents and shook their hands before driving off.

'They said that if they knew they were Muslim girls they wouldn't have abducted them,' Mdada said. 'They warned the girls that they should stay away from school and swore that if they came back and found any girl in school, they'd abduct them again and never give them back.'

Boko Haram means 'Western education is a sin' in the local Hausa language and one of the group's aims has been to prevent what they perceive as non-Islamic style education.

The girls were released 'through back-channel efforts and with the help of some friends of the country', according to a statement from Lai Mohammed, Nigeria's information minister.

However some details of the release are unclear and an Amnesty International report claimed police and security forces had known that Boko Haram were planning to kidnap the pupils but did nothing about it.

The girls have now been taken away from their families again and driven to Abuja, Nigeria's capital, where they are thought to be meeting the president, Muhammadu Buhari.