Alpha Conde declared winner in Guinea president polls
Mr Conde and his rival both declared victory earlier on Monday
Opposition leader Alpha Conde has won the presidential run-off in Guinea, the electoral commission has said.
Mr Conde gained 52.5% of votes in the 7 November poll against former Prime Minister Cellou Dalein Diallo, according to provisional results.
The elections aim to mark the end of 52 years of authoritarian rule, but have been marred by violence and delays.
Mr Diallo, who has alleged fraud, earlier said he would not accept the outcome of the polls.
After the announcement, Mr Conde, 72, reached out to Mr Diallo, saying: "The time has come to join hands".
Both Mr Conde and Mr Diallo - who won the first round of polls - earlier declared victory ahead of results.
UN Secretary General Ban Ki-moon meanwhile released a statement calling for Guineans "in the national interest, to accept the results of the elections and to resolve any difference through legal means."
Supporters of Mr Conde celebrated the outcome in the capital, Conakry.
"We won," one supporter told Reuters. "(Conde) has suffered too much but that is all over now."
According to the electoral commission, Mr Conde received 1.47m votes in the country's 28 districts, against 1.3m votes, or 47.5%, for Mr Diallo.
Voter turn-out in the West African state was 67%, the commission added.
Mr Diallo and Mr Conde come from Guinea's two largest ethnic groups, the Peul and Malinke.
Mr Diallo earlier said he would not accept results based on fraud, claiming that supporters in two counties were too intimidated to vote after ethnic riots against the Peul in the days before the poll.
Ahead of the announcement, tensions in the capital, Conakry, sparked protests and riots by supporters of Mr Diallo.
Despite a ban on political demonstrations, activists took to the street, burnt tyres and set up barricades in parts of the capital. Several people were arrested and injured in clashes with riot police.
Some members of Mr Conde's Malinke community have alleged that they have been attacked and had their homes burnt down by Mr Diallo's supporters.
"They said that if Cellou (Diallo) does not win that they will kill all the Malinke," said 60-year-old Moussa Dioubate, who said some men had broken the windows in his house and set the mattress on fire.
International observers said the election was carried out peacefully, while France's former foreign minister, Bernard Kouchner, described the vote a "historic achievement after 50 years of dictatorship".
Mr Diallo gained 44% of the first round vote in June, compared with 18% for Mr Conde. The opposition leader later complained of fraud.
Guinea has been led since January by the interim government of Gen Sekouba Konate, who took over from the leaders of a 2008 coup.
The military seized power after the death of autocratic President Lansana Conte, who ruled the mineral-rich state for 24 years.
Guinea is the world's largest exporter of the aluminium ore bauxite, yet the country is one of the poorest in West Africa.