Ghana's opposition challenger for the country's presidency, John Atta Mills, is retaining his slight lead in a run-off election as the final votes are counted.

According to the Electoral Commission of Ghana, on Monday evening Atta Mills had 52.1 percent of votes counted so far and ruling party candidate Nana Akufo-Addo had 47.9 percent. This was after votes had been counted in 200 of the country's 230 constituencies.

Provisional results published by the civil society group, the African Elections Project, reflecting results in 226 constituencies, showed Atta Mills holding a narrower lead: 50.52 percent to Akufo-Addo's 49.48 percent.

Final results are scheduled to be announced by the commission at noon on Tuesday.

The commission described its statistics as "provisional figures of the certified results." It said Atta Mills, who is standing for the National Democratic Congress (NDC) of former ruler Jerry Rawlings, had won 4,065,883 votes. Akufo-Addo, of the New Patriotic Party (NPP) of outgoing President John Kufuor, had 3,737,655 votes.

The run-off was held on Sunday after neither candidate received the required majority of votes in the first round of voting on December 7. The NDC won a clear majority of seats in Parliament on December 7.