Nigerian election winner Muhammadu Buhari has congratulated outgoing President Goodluck Jonathan for peacefully relinquishing power, a day after becoming the first Nigerian politician to unseat a sitting leader at the ballot box.

"President Jonathan was a worthy opponent and I extend the hand of fellowship to him," Buhari told journalists and supporters to loud applause on Wednesday.

"We have proven to the world that we are people who have embraced democracy. We have put one-party state behind us."

The margin of victory - Buhari got 15.4 million votes to Jonathan's 13.3 million - was enough to prevent any legal challenge.

In an unprecedented step, Jonathan called Buhari to concede defeat and issued a statement urging his supporters to accept the result, a signal of deepening democracy in Africa's most populous nation that few had expected.
 Nigeria's election explained in one minute
He urged his supporters to follow "due process" in channelling their frustrations at losing the election amid fear of violence.
"Nobody's ambition is worth the blood of any Nigerian," he said in a statement issued after his election defeat.
"The unity, stability and progress of our dear country is more important than anything else."
The rules state he must officially handover on May 29.

His rival All Progressives Congress Party (APC) wasted no time in crowning him a "hero" for his good sportsmanship.

Jonathan's People's Democratic Party (PDP) has been in charge since the end of army rule in 1999 but had been losing support due to several oil sector corruption scandals and killings by rebel group Boko Haram in the northeast.

"You voted for change and now change has come," Buhari said.
Former military ruler Buhari became the first Nigerian to defeat a sitting president through the ballot box.
Al Jazeera's Yvonne Ndege, reporting from the capital Abuja, said Buhari was declared the winner after he gained 2.7 million more votes than his rival, incumbent President Goodluck Jonathan.
"There had always been this fear that he might not want to concede, but he will remain a hero for this move. The tension will go down dramatically," Lai Mohammed, spokesman for the APC, said.
Victory for Buhari marks the first time in Nigeria's history that an opposition party has democratically taken control of the country from the ruling party.
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Supporters of Buhari in Kano state celebrated his victory [Tom Saater/Al Jazeera]
Al Jazeera's Haru Mutasa, reporting from Lagos, said there was shock that Jonathan had congratulated Buhari and that violence had not followed the announcement. In the 2011 election, more than 800 people were killed in protests after Buhari was defeated by Jonathan.
"The announcement has been greeted with celebrations across the country," Mutasa said. "Many people are excited and hope this will mark a new beginning and move the country forward."
Hundreds of Buhari's supporters gathered to celebrate outside his home in Abuja, with some brandishing brooms to symbolise his promise to clean up corruption.
His supporters told Al Jazeera that the vote was "free, fair and without irregularities" as the country ushered in a new era.
"We don't have roads, electricity and the youth are looking for jobs," one supporter said. "The people wanted change and change has now come."
"Nigeria has been reduced to a failed state." - What Muhammadu Buhari told Al Jazeera last month
Jonathan, whose five years in office have been plagued by corruption scandals and an insurgency by the Boko Haram group, was trailing by around 500,000 votes before votes in pro-opposition areas were counted.
There was a brief protest by Jonathan's Peoples Democratic Party (PDP) before the counting had resumed on Tuesday.

Former Niger Delta minister Godsday Orubebe accused elections chief Attahiru Jega of being "partial" and "selective".

Orubebe claimed Jega had refused to investigate PDP complaints about big wins by Buhari in northern states but had launched a probe into claims by the APC of irregularities in Rivers.
Jega said later: "I don't believe that the allegations are substantial enough to require the cancellation or rescheduling of the elections in Rivers state. We will take the results."
International observers gave broadly positive reactions to the conduct of the vote, despite late delivery of election materials and technical glitches with new voter authentication devices.

Nigeria's Transition Monitoring Group, which had observers across the country, said: "These issues did not systematically disadvantage any candidate or party."
Buhari supporters celebrate in Kano [Reuters]
Source: Al Jazeera