Thousands of Mr Mahama's supporters packed Independence Square in the capital, Accra, for the ceremony, reports the BBC's Sammy Darko from the scene.

BBC: John Mahama: Ghana's NPP boycotts swearing in

It would include an IT university, a residential area, a hospital, as well as social and sporting amenities, the BBC's Sammy Darko reports from Accra.

BBC: Ghana's John Mahama launches Hope City project

The BBC's Sammy Darko in the capital, Accra, says the party has calculated that there were 1.34 million extra votes cast, which if withdrawn from the final tally would make Mr Akufo-Addo the winner.

BBC: Ghana election: NPP challenges John Mahama's victory