Oby Ezekwesili, the co-founder of a group campaigning for the release of more than 200 girls kidnapped by Boko Haram in 2014, has announced that she will run for president in Nigeria next year.

She will be the first prominent woman to challenge an incumbent president.

Mrs Ezekwesili, a vocal critic of the Nigerian government, is a former vice-president of the World Bank and also served as a cabinet minister under former President Olusegun Obasanjo.

In February's elections she will face front-runners President Muhammadu Buhari of the governing APC and former Vice-President Atiku Abubakar who has been announced as the candidate of the main opposition party, the PDP.

Some analysts believe Mrs Ezekwesili's presence in the race could disrupt what would have been a straight contest between Nigeria's two dominant parties, which have supplied every president since the end of military rule in 1999.