According to Nigeria's independent electoral commission, ruling party candidate Umaru Yar'Adua of the People's Democratic party took 70 per cent of the popular vote, winning 24.6 million votes.
His nearest rival, Muhammadu Buhari, received 6.6 million, giving Mr Yar-Adua what appears to be clear victory.
But criticism of the poll has been widespread thanks to reports of stolen ballot boxes, police opening fire on crowds, the abduction of election officials and the deaths of around 200 people.
"The elections have not lived up to the hopes and expectations of the Nigerian people and the process cannot be considered to be credible," Max Van den Berg, chief EU observer, said.
Mr Buhari yesterday said he would reject the election result while the other main contender, vice president Atiku Abubakar, was quoted by the AFP news agency as describing Saturday's poll as "the worst election ever seen".
Nigeria's election is the first democratic handover from one civilian president to another since the country gained independence from Britain in 1960.
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