Nigeria has announced initial results after a tight election for the presidency of Africa's most populous nation, marked by widespread voting delays and early accusations of attempts to manipulate ballot counts, AFP reports.

Nearly 90 million were eligible to vote on Saturday for a successor to President Muhammadu Buhari, with many hoping a new leader would do a better job tackling insecurity, economic malaise and growing poverty.

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The election went ahead mostly peacefully, despite some ransacked polling stations and late starts at many others. Voters stayed up late at night in many locations to observe the count and "protect" the ballots.

The election pits former Lagos governor Bola Tinubu, 70, of the ruling All Progressives Congress (APC) against former vice president 76-year-old Atiku Abubakar, of the Peoples Democratic Party (PDP).

But for the first time since the end of military rule in 1999, a surprise third-party candidate, Labour Party&039;s Peter Obi, has challenged the APC and PDP dominance with a message of change and an appeal to younger voters.

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Announcing first results state by state, Independent National Electoral Commission (INEC) on Sunday said APC's Tinubu easily won small, southwestern Ekiti state with PDP coming second.

Malpractice

The result was very preliminary in a country almost equally divided between a mostly Muslim north and a predominantly Christian south. Voting has often been determined by large key states such as Lagos and northwestern Kano and Kaduna.

To win the presidency, a candidate must get the most votes, but also win at least 25 percent of votes cast in two-thirds of Nigeria's 36 states to reflect wide representation.

But slow uploading of results to INEC's online website on Sunday provoked worries of electoral malpractice in a country with a history of ballot rigging and vote buying.

"Let Nigeria decide O! @inecigeria," Nigerian Afrobeats star and Grammy Awards winner Burna Boy wrote on Twitter. "No try any result magic."

PDP's candidate Abubakar urged INEC to upload the results immediately after accusing some state governors of trying to compromise the results.

"It will be a disservice to Nigerians and a negation to democracy for anyone to subvert the will of the people as freely expressed in their votes of yesterday," he said in a statement.

When he was defeated by Buhari in the 2019 election, Abubakar claimed massive fraud, but the Supreme Court eventually rejected his challenge.

Labour Party chairman Julius Abure also accused election officials of failing to upload results from parts of Lagos and southern Delta State to help the ruling APC's candidate.

Observers group Yiaga Africa said it was "deeply concerned with the delay" in results.

But INEC said problems with uploading results on its IReV data page were due "technical hitches" and there was no risk of tampering.

"The commission wishes to assure Nigerians that the challenges are not due to any intrusion or sabotage of our systems," it said in a statement.

"It is important to avoid statements and actions that can heat up the polity at this time."

'Race is open'

In Lagos and other cities, crowds stormed polling stations late on Saturday as electoral officials tallied the first results by hand and read out the counts before transmitting them to the central database.

On Sunday morning, people gathered at a newspaper stand in the Falomo area of Lagos, eager for results to come in and expressing hope this election would bring change.

"Last time, we knew Buhari was going to be re-elected, there was no excitement," said mechanic Orubibi Dighobo. "But this time is so different, the race is open and there is hope."

The competitive race has some analysts forecasting an unprecedented runoff between the two frontrunners if no candidate meets election requirements. It would have to be organised within 21 days.

The success of Nigeria's vote will be closely watched in West Africa, where coups in Mali and Burkina Faso and growing Islamist militancy have taken democracy in the region back a step.

A range of challenges

Buhari, a former army general first elected in 2015, will step down after two terms in office. His critics say he failed in his key promises to make Nigeria safer.

Whoever wins the election must quickly get to grips with Africa's largest economy and top oil producer, beset by problems from a grinding jihadist war in the northeast to double-digit inflation.

APC's candidate Tinubu, a long-time political kingmaker and southern ethnic Yoruba Muslim, says "It's my turn" for the presidency. He says his experience as Lagos governor will count.

He faces a familiar rival -- PDP candidate Abubakar, a Muslim from the northeast who is on his sixth bid for the top job and touts his business experience to fix the economy.

But both are old guard figures who have fought off past corruption accusations, and the emergence of Obi, a Christian ethnic Igbo from the southeast, threw the race open.