Guinea poll losers protest in the capital
Supporters of the defeated candidate in Guinea's presidential election, Cellou Dalein Diallo, have been protesting in the streets about the poll results.
The security forces have been firing tear gas in the capital and violence has been reported in some other areas.
Mr Diallo appealed for calm and said he would challenge the results in court.
Veteran opposition leader Alpha Conde, who won with more than 52% of the vote, said he wants to lead a process of national reconciliation.
The elections mark an end of 52 years of authoritarian rule, but since the first round in June, won by Mr Diallo - a former prime minister - the process has been marred by violence and delays.
According to the electoral commission, Mr Conde received 1.47 million votes in the country's 28 districts, against 1.3 million votes, or 47.5%, for Mr Diallo.
Correspondents say Mr Diallo's supporters, in some parts of the capital, Conakry, were throwing stones when tear gas was fired to disperse the demonstration.
Several people were arrested and injured in similar clashes with riot police on Monday - before the the results were out.
After the results were declared on Monday night, Mr Conde, 72, reached out to Mr Diallo, saying: "The time has come to join hands.
"I dedicate this victory to all Guineans without any distinction - to all of you who voted for me and to all of those who made a different choice," he said.
"Time has come to work together in a spirit of concordance and fraternity. I will be the president of change. I will be the president of national reconciliation and progress."
The BBC's Alhassan Sillah in Conakry says the overnight celebrations of Mr Conde's supporters have been marred by the violence.
He says residents in some parts of the capital are too scared to attend special prayers for the Eid al-Adha religious festival.
Mr Diallo says he believes there was fraud in the second round, and will mount a challenge to the results in the Supreme Court
"We must, at all costs, maintain peace in this country," he told Radio France International.
Before the run-off both candidates, who come from Guinea's two largest ethnic groups, the Peul and Malinke, had promised to include each other in government.
Despite their economic dominance, a member of the Peul community has never been president. The Malinke are heavily represented in the ruling military junta
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.