Voting in Ghana for a new president and parliament has entered its second day after technical glitches led to long delays in some areas.

Breakdowns in a new biometric voting system meant many were unable to cast ballots on Friday.

A tight race is expected between the two main candidates - incumbent President John Dramani Mahama and opposition leader Nana Akufo-Addo.

Ghanaian electoral observers said no serious incidents had been reported.

It was not clear how many polling stations had been affected by Friday's glitches. The new biometric system requires electronic fingerprints from voters.

"We are talking about isolated instances - it is not a mass problem," electoral commission chief Kwado Afari-Gyan told AFP news agency.

Results had been expected as early as Sunday but it was unclear if the timeframe would remain after the extension.

A second round is possible on 28 December if no candidate wins an outright majority. Narrow majority

Mr Mahama, speaking after casting his vote on Friday, said the elections would "go down in history as the best ever to be held in Ghana".

Mr Akufo-Addo expressed hope that the polls would remain peaceful.

Mr Mahama took over as president after John Atta Mills died in July. His National Democratic Congress is also defending a narrow parliamentary majority.

Ghana has seen five elections since military rule ended in 1992 but analysts say the stakes are higher than ever as commercial oil production that began in 2010 is expected to expand.

Mr Mahama wants to spend Ghana's new wealth on large investments in infrastructure, while Mr Akufo-Addo is advocating free secondary education.

As a top exporter of cocoa and gold, Ghana is one of the world's fastest-growing economies.

In 2011 it saw economic growth of 14% and experts predict growth of 8% for 2012 and in 2013.