Clashes broke out between youths and police in the Guinean capital Conakry, where opposition activists had called a "ghost town" demonstration a day after protests turned violent.
At least 15 people have been injured in the clashes, officials said on Friday. Unrest has been growing in the West African state over delays to a long-awaited parliamentary election, which is scheduled for next month. The vote is supposed to complete a transition from military to civilian rule.
Anti-government protesters shut down large parts of Conakry as youths put up barricades across roads in the suburbs, burning tyres to block major highways into the city centre, witnesses told the AFP news agency.
As traffic ground to a halt, security forces were deployed to dismantle the barricades and fighting broke out between police and protesters.
Government spokesman Damantang Albert Camara said in a statement the "ghost town" protest had turned into "a day of vandalism, assaults on representatives of law enforcement" without specifying the number of people wounded.
"Bystanders and hooligans... attacked peaceful civilian populations and private businesses," said Camara, adding that police were deployed "to return calm, neutralise the law-breakers and make safe the people and their property".
The clashes follow protests which degenerated into violence on Thursday, leaving several dead. The government said one person had been killed by gunfire while another had died "by accident" but opposition activists put the toll at six.
Camara said normality had returned to "all parts of the capital" although witnesses said schools and petrol stations remained closed in the suburbs.
At least 17 people have been killed in clashes between anti-government protesters and security forces at a series of opposition rallies in Conakry in recent weeks.
Discontent has spilled over into deadly violence in the west African country, where activists have accused President Alpha Conde of planning to rig upcoming elections planned for June 30.
The last legislative elections were held in 2002 under then president Lansana Conte, who ruled the former French colony for 24 years until his death in December 2008, which prompted a disastrous coup marked by extreme police brutality.
Al Jazeera's Dominic Kane said that Guinea's parliament has not met since 2008. He said the opposition sees the elections as a vehicle for ousting the government and to use the vast natural resources Guinea possesses for the benefit of all.
The United Nations Security Council said in a statement in April that it was "worried about instability" in Guinea and called for calm in the restive nation.