Nigeria's Goodluck Jonathan has been declared winner of presidential elections in a landmark vote that exposed regional tensions and led to deadly rioting in the mainly Muslim north.
Jonathan, the incumbent and first president from the southern oil-producing Niger Delta region, won 57 percent of the vote in Africa's most populous nation, easily beating his northern rival, ex-military ruler Muhammadu Buhari.
Final results declared Monday evening, which the opposition rejected, gave Jonathan 22.5 million votes, while Buhari scored 12.2 million votes for 31 percent.
|Nigerian President Goodluck Jonathan (C) is congratulated by cabinet members after being declared winner of presidential elections|
The president reached out to his opponents in a victory speech and called for national unity, while also saying that Africa's largest oil producer had shown itself capable of holding fair polls.
"I congratulate the candidates of the other political parties," he said. "I regard them not as opponents, but as partners."
Jonathan mentioned by name the other main candidates in the race, including Buhari, saying he wanted to pay tribute to them.
Observers have hailed the conduct of the poll as a major step forward for a nation with a history of violent and deeply flawed elections.
British Foreign Secretary William Hague congratulated Jonathan and said the election "appears to be the most credible since the end of military rule in 1999".
A group of local observers, Project 2011 Swift Count, said Monday night that the official results matched up closely with its sample of 1,441 polling units. It called the results an "accurate reflection of how Nigerians voted".
But problems clearly remained, and concerns were raised over Jonathan's extraordinarily high totals in certain states, including his native Bayelsa, where he took 99.63 percent.
The vote showed a country deeply divided between its predominately Christian south and economically marginalised north, where deadly riots broke out and eventually spread to some 14 states after results began to be released.
An unspecified number of people were killed in the main northern city of Kano when homes and shops were attacked, and also in Gombe when a home was set ablaze and in Kaduna, where mobs had stopped people on the highway.
Vice President Namadi Sambo's home was also torched and a 24-hour curfew had been imposed in his native state of Kaduna. A prison was raided and inmates set free.
A spokesman for the national emergency management agency, Yushau Shuaib, confirmed that deaths occurred but declined to provide figures out of fears of reprisals.
Jonathan, from a family of canoe makers and who rose to the presidency in May 2010 after the death of his predecessor, Umaru Yar'Adua, condemned the violence.
"I enjoin our political and religious leaders in their usual sense of patriotism to call on their followers to eschew all acts of bitterness and violence," he said.
"As I have always stated, nobody?s political ambition is worth the blood of any Nigerian."
Buhari's party also condemned the violence, but he had not spoken publicly after the results were announced.
The riots that began sporadically over the weekend due to rigging allegations quickly spread across the north and parts of central Nigeria on Monday.
Churches were burnt and mobs roamed in a number of states, armed with sticks and setting bonfires alight in the streets. Protesters early in the day fought running battles with soldiers in Kano.
Police said the rioting had been instigated by those unhappy with the results, saying it was "neither ethnic nor religious". The military made similar comments and warned it was ready to act.
Curfews in place in various parts of the north appeared to have considerably calmed the situation.
Many analysts had feared the deepening of regional divisions that showed up in the results in a country as fractious as Nigeria, roughly split between Christians and Muslims and with some 250 ethnic groups.
In the months leading up to the polls, the ruling Peoples Democratic Party sought to heal internal rifts over whether it should abandon Jonathan, a southern Christian, in favour of a candidate from the north.
Jonathan, 53, won out in the end, but bitterness remained.
Buhari, a 69-year-old Muslim, has built a reputation as a fighter of corruption, but his "war against indiscipline" during his regime in the 1980s was also accused of outrageous rights abuses.
Many in the north saw in him an opportunity to return power to their region.