Ghana incumbent President John Dramani Mahama won a new term with 50.7 percent of ballots cast in the West African state's election, the head of the Electoral Commission announced.
"Based on the results, I declare President John Dramani Mahama president elect," Kwadwo Afari-Gyan told a newsconference on Sunday in the capital Accra.
Ghana's main opposition party declared electoral fraud after election results showed the candidate of the governing National Democratic Congress was holding a slim lead.
The results came after the National Patriotic Party called on the electoral commission to delay the official announcement of the results, raising concerns about the conduct of the vote in a nation seen as a stable democracy in an unstable region.
Privately owned Joy News television said John Dramani Mahama, 54, had 50.03 per cent of the votes against Akufo-Addo's 48.05 per cent based on provisional results from 261 of 275 districts.
It said its findings were based on trends of pre-tallied votes in addition to an analysis of outstanding districts.
"It will be unfortunate for the EC [Election Commission] to go ahead to announce the elections," Jake Obetsebi-Lamptey, the NPP chairman, announced in the capital Accra.
"We have significant problems and that need to be looked at ... These results cannot be forced down the throat of the people of Ghana."
He said the party had raised complaints to the electoral commission in a letter requesting an audit of results before their release.
But Kwadwo Afari-Gyan, an election commissioner, told Reuters news agency on Sunday he was not yet aware of the NPP complaint.
The vote, which started on Friday and stretched into Saturday amid technical problems, is seen as a test of whether Ghana can maintain 30 years of stability and progress in a region better known for coups, civil wars and corruption.
There were a total of eight presidential candidates. In the event that any of the candidates fail to receive at least 50 per cent of the votes, a run-off vote would be held on December 28.
Mahama was vice-president until July when he assumed the presidency after his predecessor John Atta Mills died due to an illness.