Guinean police have clashed with several hundred protesters in the capital, Conakry, as the country awaits the results of recent polls.
Tensions are rising in the West African nation after partial results suggested the outcome of the 7 November presidential run-off was too close to call.
Both candidates have declared victory, amid allegations of fraud.
The polls aim to end 52 years of authoritarian rule.
The electoral commission says it will publish provisional results later on Monday, after missing earlier deadlines.
Demonstrators on the streets of the capital on Monday burned tyres and threw stones at security forces in an area seen as loyal to candidate and former Prime Minister Cellou Dalein Diallo.
"We managed to disperse the demonstration," a senior police official told Reuters.
Partial results earlier from half of the electorate indicated the race was tight, with Mr Diallo leading slightly over rival opposition leader Alpha Conde.
Mr Diallo and Mr Conde come from Guinea's two largest ethnic groups, the Peul and Malinke.
Earlier on Monday, Mr Conde declared victory, claiming he had won three out of four regions.
"I have won four out of five districts in Conakry, all of the Lower Guinea prefectures except for Boke, all of the Forest prefectures and Upper Guinea. How could I not win?" he said at a news conference.
Mr Diallo followed suit and claimed he had won, but said there had been "massive fraud at all levels" and that he would not accept the results.
He claimed that his supporters in the counties of Kouroussa and Siguiri were too intimidated to vote after ethnic riots against the Peul in the days before the poll.
Electoral commission chairman Siaka Sangare on Sunday said that all claims of fraud had been treated "with the maximum attention".
Meanwhile members of Mr Conde's Malinke community have claimed they have been attacked by Mr Diallo's supporters.
International observers said the election was carried out peacefully and said there was a high turnout, but they have also warned the vote was just the start of the process.
Mr Sangare previously said election results would be published as soon as they came in, but the National Independent Election Commission website has not yet released any second round results.
Mr Diallo gained 44% of the first round vote in June, compared with 18% for Mr Conde. The opposition leader later complained of fraud.
Bernard Kouchner, until this week foreign minister of former colonial power France, called the vote a "historic achievement after 50 years of dictatorship".
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.
Despite being Guinea's largest ethnic group, a Peul has never been president. The Malinke are heavily represented in the ruling military junta.
Guinea is the world's largest exporter of the aluminium ore bauxite, yet the country is one of the poorest in West Africa.