Voting has started in Ghana in a run-off presidential election that will decide who leads the West African nation into an era of oil production.

Some 12.5 million people are eligible to cast ballots in the  voting which began at 7 am (0700 GMT) on Sunday.

Neither Nana Akufo-Addo of the ruling New Patriotic Party (NPP) nor John Atta Mills of the National Democratic Congress (NDC) were able to score a decisive victory in the first round in early December.

Akufo-Addo got marginally more votes than Atta Mills, but the other six candidates polled enough to prevent him from crossing the 50 per cent mark.

The NDC complained about irregularities in voting in the first round, which had a turnout of around 70 per cent.

However, the EU's election monitoring team hailed the poll as a credit to African democracy, which sorely needs a boost after electoral chaos in Kenya and Zimbabwe and coups in Mauritania and Guinea this year.

The run-off is expected to be a close-fought affair, with both candidates in with a strong chance of victory.

The NPP lost its parliamentary majority in elections held at the same time as the first round of the presidential poll.

Atta Mills and Akufo-Addoe are vying to replace John Kufuor, who must step down in January after serving two terms.