Nigerians were still voting in a national election on Sunday in a few parts of the country where technical and other glitches prevented voting from taking place as scheduled the previous day.
Vote-counting was already under way in other areas after Saturday's presidential and parliamentary election.
The race to succeed President Muhammadu Buhari was expected to be the closest in the country's history, with candidates from two parties that have alternated in power since the end of army rule in 1999 facing an unusually a strong challenge from a minor party candidate popular among young voters.
A Reuters reporter saw people casting their votes at polling stations in Yenagoa city, in Nigeria's oil-producing south.
“The whole process is an absolute mess,” Preye Iti, a 60-year-old civil servant, said before voting in the city, where voting could not take place in some parts on Saturday because election officers and materials did not arrive on time.
“I waited from 8.30am to 6.30pm yesterday. Now I'm back here at 8.30 again.”
Besides Yenagoa, voting was also expected to continue in some parts of north-eastern Borno state on Sunday, where voting machines failed to work the previous day.
It was not clear exactly how many of the country's 93 million registered voters were unable to cast a ballot on Saturday.
Voting in many parts of the country of 200 million people went smoothly on Saturday, and while there were scattered incidents of violence and intimidation, it was not on the scale seen in previous elections.
The electoral commission said late on Saturday that official nationwide results could be expected from late on Sunday evening. The final election tally is expected within five days.
The main presidential contenders are former Lagos governor Bola Tinubu, 70, of the ruling All Progressives Congress, former vice president Atiku Abubakar, 76, of the main opposition Peoples Democratic Party, and former Anambra State governor Peter Obi, 61, of the smaller Labour Party.
Outgoing President Buhari, a retired army general who was also a military ruler in the 1980s, is stepping down after winning two previous elections and serving the maximum eight years permitted by the constitution.
Whoever wins will face a litany of crises in Nigeria, which is Africa's top oil producer and the continent's most populous nation.
The country is struggling with Islamist insurgencies in the north-east, an epidemic of kidnappings for ransom, conflict between herders and farmers, shortages of cash, fuel and power, and deep-rooted corruption and poverty.
