* President Buhari, opposition’s Atiku leading contenders
* Nigeria is Africa’s biggest economy, top oil producer
* Blasts heard in city of Maiduguri – Reuters witnesses
* GRAPHIC-Nigeria presidential election: tmsnrt.rs/2E6qkDO (Adds INEC extends voting hours, presidential contender, Borno governor)
By James Macharia and Ahmed Kingimi
ABUJA/MAIDUGURI, Feb 23 (Reuters) – Nigeria began counting votes in Saturday’s closely-fought presidential election although the electoral commission extended voting hours in some places where polling stations opened late or ballot machines malfunctioned.
President Muhammadu Buhari and his main challenger, businessman Atiku Abubakar, both said they were confident of victory when casting their ballots in an election which has already been delayed by a week.
Analysts say the vote in Africa’s biggest economic power is too close to call, with the outcome set to hinge on which man voters trust the most to revamp an economy still struggling to recover from a 2016 recession.
Buhari, a former military ruler who was later elected president, is seeking a second term in charge of Africa’s most populous nation and top crude producer. Atiku, a former vice president, has pledged to expand the role of the private sector.
The two men lead a field of more than 70 candidates in an election which the commission postponed last Saturday just hours before voting was due to begin, citing logistical issues.
Voting had been completed in some areas across Nigeria and counting of ballots was taking place, Reuters witnesses said.
Senior Independent National Electoral Commission (INEC) official Festus Okoye said the commission had extended hours in polling stations that had experienced delays.
He also said problems encountered during the voting, including security issues, were being addressed. These included malfunctioning of voter card machines which would be replaced.
“We are on top of the situation and we are confident that as we progress in this particular election, most of the issues that arisen relating to this particular election will be addressed,” Okoye said.
The country has 72.8 million eligible voters.
Buhari, who voted in his hometown of Daura in the northern state of Katsina, said: “I will congratulate myself, I’m going to be the winner” when asked by reporters if he would congratulate his rival, should Atiku win the election.
Atiku later cast his ballot in the eastern Adamawa state.
“I am impressed by the turnout of the people,” he told reporters shortly after voting.
“I look forward to a successful transition,” he said.
Voting officially began at 8:00 a.m. local time (0700 GMT) and was due to close at 2:00 p.m. but Kingsley Moghalu, a presidential candidate for the Young Progressives Party, said he had only managed to vote at noon in the southeastern state of Anambra. He said polls opened two hours late and machines to read voting cards were not working.
“If as a presidential candidate my polling unit can be treated in this manner, I can imagine what a lot of Nigerians are going through in many parts of the country,” he said.
Other voters echoed his concerns.
“I’ve been to 10 polling units today. I’ve been redirected many times,” said Victor Kanoba a voter in Lagos.
John Tomaszewski, an observer with the joint U.S. National Democratic Institute and International Republican Institute delegation, said delays had been somewhat expected given the logistical challenge of getting materials to the polling stations in time for opening.
“Logistics weren’t properly managed despite the postponement of the polls,” said Idayat Hassan, director of Abuja-based think tank Centre for Democracy and Development, which is also observing the election.
However, in Lagos’ business district of Victoria Island, Reginald Anthony, 45, who runs a transport business, said: “We are seeing a transparent election, everything is open for everyone to see”.
After voting in the northern Kano state, Hadisa Hayatu, a 38-year old housewife, said: “I voted for Buhari because he has assured us that he is going to build on what he has done on security and other issues.”
An Atiku supporter in Kano, stylist Laurie Isaac, 27, said: “We need change. I need more work. I need my salary to increase.”
In the country’s northeast, where insurgent groups like Boko Haram and Islamic State West Africa Province have waged a decade-long war, blasts were heard in the city of Maiduguri, the capital of Borno state. Boko Haram had warned people not to vote.
Security sources said militants had struck at parts of Maiduguri and a Reuters witness said he had heard gun shots and Nigerian air force jets were flying overhead.
Colonel Sagir Musa, acting director of army public relations, said there had not been an attack on any part of Maiduguri, where activity had been part of an exercise by the military.
“Our people defied Boko Haram threats and came out,” Kashim Shettima, Borno’s governor, said after voting in Maiduguri. Shettima’s motorcade was attacked by insurgents on Feb. 12 on route to an election rally.
“The world should know we may not have a perfect exercise but the process is still OK.”
Reporting by Paul Carsten, Seun Sanni, Aaron Ross, Abraham
Achirga, Adewale Kolawole, Afolabi Sotunde, Ardo Hazzad, Didi
Akinyelure, Garba Muhammed, Mike Oboh, Nneka Chile, Ola Lanre,
Percy Dabang, Camillus Eboh, Christian Merenini and Tife
Writing by James Macharia; Editing by Alexis Akwagyiram and Toby