All three Nigerian front-runners claim they are on path to presidency

Result of election to find Muhammadu Buhari's successor not expected for several days

Bola Tinubu of the All Progressives Congress (APC), centre, with his wife Oluremi, right, after winning the presidential elections in Abuja, Nigeria. AP

Supporters of Mr Tinubu celebrate after he was declared the winner, at the party's campaign headquarters in Abuja. Reuters

APC supporters celebrate in Lagos. AFP

Mr Tinubu, 70, won 8.8 million votes against 6.9 million for opposition People's Democratic Party candidate Atiku Abubakar and the Labour Party's Peter Obi, with 6.1 million. AFP

The announcement of the result is expected to lead to a court challenge by the two main opponents. AFP

The ruling APC party urged the opposition to accept defeat and not cause trouble. AP

Electoral commission chairman Mahmood Yakubu, centre, looks on as results for individual states are read out in Abuja. AP

Besides having to get Nigeria's finances back on track, Mr Tinubu will need to quash violence perpetrated by militants, secessionists and armed bandits across the country. EPA

A man takes part in a protest against the electoral commission in Abuja. AP

Nigerian soldiers are stationed near a market in Lagos to prevent election-related violence. Reuters

Polling officers collate the results at the electoral commission's office in Lagos. EPA

A voter casts her ballot at a polling station in Amatutu during Nigeria's presidential election. AFP

A woman writes her name on an unofficial list of voters. AFP

People queue to write their names on an unofficial list of voters in Abuja. AFP

A voter gets her information checked by an Independent National Electoral Commission official at a polling station in Agege, Lagos. AFP

An official confirms the details of a voter at a polling station in Agege. AFP

Voters queuing to vote. AFP

A voter casts his ballot at a polling station in Agege. AFP

Nigeria's Labour party candidate Peter Obi speaks to journalists before casting his vote. AP Photo

An official sets up the Bimodal Voter Accreditation System in Amatutu. AFP

Polls open at the University of Ibadan. AFP

Voters queue outside a polling station in Kano. AFP

Party agents look at polling station information in Kano. AFP

The three front-runners in Nigeria’s hotly contested presidential election each claimed to be heading for victory on Monday as preliminary results trickled in two days after Africa's most populous nation went to the polls.

Only four of Nigeria's 36 states had officially announced results by midday, with three of those going to Bola Tinubu of the ruling All Progressive Congress (APC) party. The fourth was won by Atiku Abubakar, of the main opposition People's Democratic Party (PDP).

Also in the mix is the Labour Party candidate Peter Obi, who enjoys widespread support among the youth. A winner is not expected to be announced until at least Tuesday. It took four days for officials to declare a winner in the 2019 election.

A run-off election will be held if no candidate secures at least a quarter of the votes from two-thirds of Nigeria’s 36 states and the capital city, in addition to receiving the highest number of votes.

On Monday, the African Union observer mission said voting had been delayed in more than 80 per cent of polling units, mainly because of logistical challenges caused by Nigeria’s currency swap programme.

The redesign of the Nigerian bank note, the naira, caused cash shortages nationwide and voters and poll workers had difficulties getting to polling stations on Saturday. Voters in some states had to wait until late in the evening to cast ballots, while in other states voting continued on Sunday.

Observers from the AU and the West African regional bloc known as Ecowas said the election was generally “encouraging” except for isolated cases of violence that disrupted voting in some states.

After Mr Tinubu's victory in Ekiti state, the incumbent party said it was on course to stay in power.

“If the information we are beginning to receive from various parts of the country is anything to go by, one has every reason to be optimistic that our candidate will win”, Abdullahi Adamu, the APC chairman, told the state-run News Agency of Nigeria.

The PDP claimed victory for Mr Abubakar, saying people had turned out “en masse to give their votes” to the party.

“From preliminary results, it is clear that Atiku Abubakar’s message of hope, unity, security and rebuilding of our nation has been positively received by Nigerians”, the PDP said in a statement.

The Labour Party also claimed that its candidate was winning, though Mr Obi did not win any of the states declared.

“We are far ahead and we are already leading and we are winning in 24 states”, said Yunusa Tanko, spokesman for the Labour Party.

Mr Obi is a surprise contender in what is usually a two-horse race, with his popularity surging in polls ahead of the vote. The party accused election officials of not being present in their strongholds and said some of their supporters were denied the chance to vote.

As the full results have yet to be announced, analysts caution that early unsubstantiated claims of victory will only deepen public mistrust of the electoral process and undermine the legitimacy of the polls.

“The claims by the three parties aim to motivate their voters who are urged to protect ballot boxes from rigging. But the unsubstantiated claims of victory increase the risk of protests, both peaceful and violent by disappointed voters,” said Mucahid Durmaz, senior analyst at Verisk Maplecroft, a global risk intelligence company.