Nigeria’s two biggest opposition parties have issued formal complaints over the recent presidential election.

Nigerian voters are deciding whether to keep their accidental president in power, though unease among the country’s Muslims about the Christian leader could force a runoff in the oil-rich country where elections have long been marred by fraud and violence.

Former US president George Bush and ex-British Prime Minister Tony Blair joined Nigeria’s elite at a ceremony honouring its political and business establishment, but one winner’s absence highlighted the endemic corruption and other problems plaguing the oil-rich nation.

President Olusegun Obasanjo’s ruling party has expelled the Nigeria governor charged in Britain with money laundering.