Ghana's main opposition party has boycotted the swearing-in of President

Ghana's main opposition party has boycotted the swearing-in ceremony of President John Mahama following last month's disputed elections.

The New Patriotic Party (NPP) said Mr Mahama won the election fraudulently.

Official results gave Mr Mahama 50.7% of the vote, enough to avoid a run-off against the NPP's Nana Akufo-Addo, who won 47.7%.

Ahead of his inauguration, Mr Mahama called for unity in Ghana - seen as one of Africa's most stable democracies.

Mr Mahama was Ghana's vice-president until the unexpected death of President John Atta Mills in July.

He has served since then as acting president.