All Progressives Congress (APC) presidential candidate Bola Tinubu (C-L) campaigned on his record as Lagos governor
All Progressives Congress (APC) presidential candidate Bola Tinubu (C-L) campaigned on his record as Lagos governor AFP

Ruling party candidate Bola Tinubu won Nigeria's highly disputed weekend election on Wednesday, securing the former Lagos governor his life-long ambition of the presidency of Africa's most populous democracy.

With President Muhammadu Buhari stepping down after two terms, many Nigerians hoped Saturday's vote would usher in a leader capable of tackling the country's widening insecurity, economic malaise and growing poverty.

Tinubu, candidate for All Progressives Congress (APC) party, won 8.8 million votes against 6.9 million for opposition Peoples Democratic Party (PDP) candidate Atiku Abubakar and 6.1 million for Labour Party's Peter Obi, according to final results.

The Independent National Electoral Commission, or INEC, confirmed Tinubu as president-elect after he also secured the required 25 percent of votes in two-thirds of Nigeria's 36 states and capital.

Supporters packed into the APC party campaign headquarters in Abuja, dancing to Afrobeats music to greet Tinubu, who arrived wearing a pale blue traditional robe and red cap.

"This is a serious mandate -- I hereby accept it. To serve you... To work with you and make Nigeria great," Tinubu said as supporters cheered "Jagaban", a local chieftain title.

"I appeal to my fellow contestants to let us team together. It is the only nation we have. It is one country that we must build together."

Even before the final tallies, though, Labour and PDP had already called for the vote to be cancelled, alleging massive manipulation of the results. It was not clear whether they would take their case to court.

Tinubu, 70, a long-time political kingmaker who ran on his experience as Lagos governor from 1999 to 2007, campaigned saying "It's my turn" to govern Africa's largest economy.

He promised "Renewed Hope" but faced questions from rivals over his health, past graft accusations and ties to Buhari, who many critics say failed in his promise to make Nigeria safer.

"He has done it before, and we know that he will do better than what he did in Lagos," said supporter Adenike Mutiat Abubakar, 43. "He's the man of the people, so that's why everybody wants him."

The election was a tight race for the first time since Nigeria ended military rule in 1999, after a third challenger Labour Party's Obi, 61, drew younger voters with his message of change from his two old guard rivals.

PDP's Abubakar, a 76-year-old businessman and former vice president, lost his sixth attempt at the presidency.

Saturday's voting was mostly peaceful, but was troubled by long delays at many polling stations and some intimidation by thugs, while technical hitches disrupted the uploading of results to INEC's central website, fuelling concerns over vote rigging.

"The election is irretrievably compromised," Labour Party chairman Julius Abure told reporters on Tuesday. "We demand that this sham of an election should be immediately cancelled."

INEC introduced biometric voter identification technology for the first time at the national level and its IReV central database for uploading results to improve transparency.

But opposition parties said failures in the system to upload tallies allowed for ballot manipulation and disparities in the results from the manual counts at local polling stations.

Nigerian elections have often been marred by vote-rigging, ballot buying, violence and clashes between rival parties.

But INEC dismissed opposition allegations.

"Contrary to the insinuation by both parties, results emanating from the States point to a free, fair and credible process," the INEC said.

It said parties should allow the process to run its course and then take their claims to court.

But international observers, including from the European Union, noted major logistical problems, disenfranchised voters and a lack of transparency by INEC.

In 2019, INEC was forced to delay the election by a week just hours before voting started. Abubakar cried fraud when Buhari beat him that time around, but the country's Supreme Court later tossed out his claim.

One surprise result was Obi's victory in Lagos, the state with the largest number of registered voters and the traditional bastion of Tinubu, known as the "Godfather of Lagos".

After a grassroots and social media campaign, Obi, a former Anambra State governor, managed to attract voters with a message he offered change from Nigeria's establishment politics.

The state's eponymous megacity has put Nigeria on the cultural map with its glitzy Nollywood film scene and global Afrobeats stars like Burna Boy, but nearly half of Nigerians live in poverty and inflation is in double digits.

Security challenges awaiting Nigeria's next leader are huge.

A grinding Islamist insurgency in the northeast has displaced more than two million, bandit militias carry out mass abductions in the northwest and separatists attack police in the southeast.

Nigeria is Africa's top oil producer but struggles with sporadic fuel shortages, huge energy import bills due a lack of refineries and crude theft from its wells and pipelines.

Tinubu was among three frontrunner candidates campaigning for Nigeria's presidency
Tinubu was among three frontrunner candidates campaigning for Nigeria's presidency AFP
Supporters of Nigeria's ruling party candidate, former Lagos governor Bola Tinubu, were waiting for confirmation of his election win
Supporters of Nigeria's ruling party candidate, former Lagos governor Bola Tinubu, were waiting for confirmation of his election win AFP
Tinubu faced questions over his health and his age during campaigning, though he pushed his experience as key
Tinubu faced questions over his health and his age during campaigning, though he pushed his experience as key AFP
Tinubu was among three frontrunner candidates campaigning for Nigeria's presidency
Tinubu was among three frontrunner candidates campaigning for Nigeria's presidency AFP