Guinea's opposition leader pledged to continue the protests in which at least four people have been killed unless President Alpha Conde allows prompt local elections.
Cellou Dalien Diallo said Conde had broken a 2013 U.N.-brokered deal with the opposition to organize long-overdue municipal polls before a presidential vote set for October.
The opposition accuses Conde of packing local authorities with his supporters after the five-year mandate of elected officials expired in 2010. Diallo said those officials are campaigning on Conde's behalf, making fair elections impossible.
Before talks with Diallo on Wednesday, the president has ruled out holding local elections before October, citing a decision by the Independent National Electoral Commission (CENI) that doing so would require postponing the presidential vote.
Recent protests have sparked fears of a return to the violence of 2013. More than 50 people were killed then before legislative elections in which Conde's RPG failed to win a majority. The violence deterred investors from the Guinea, a former French colony of 12 million people and the world's largest bauxite exporter.
"We will carry on with our demonstrations because it is illegal what Conde is doing and it is unfair," Diallo said in a weekend interview. "I will tell him that this electoral calendar violates the constitution ... and the electoral code."
The rise in tensions comes as the country tries to end the worst outbreak of Ebola ever recorded. The disease has killed more than 11,000 people in Guinea, neighboring Liberia and Sierra Leone.
Politics are divided along ethnic lines. Diallo comes from the Peulh tribe, Guinea's largest, whose control over the economy has stirred resentment among some other ethnic groups. Conde comes from the Malinke, the second-largest ethnic group, but has rejected accusations of exploiting ethnicity.
Diallo has alleged fraud in the 2010 presidential election - Guinea's first democratic vote since independence from France in 1958 - after he won 44 percent of the vote in the first round only to see Conde snatch a surprise victory in the runoff.
"This time, the parties of the opposition will support whichever opposition candidate reaches the second round ,because we're all fighting for change," Diallo said, adding that he was determined to win October's vote.
The opposition protests were being fueled by frustration over stagnant growth, high unemployment, crumbling infrastructure and graft, Diallo said.
The International Monetary Fund said economic growth slowed to 1.1 percent last year and it forecast zero growth this year amid a slump in metals prices. The finance minister told Reuters in March that economic losses from Ebola may total $2 billion.
Last year, Guinea ranked 145th of 175 countries in Transparency International's rankings of corruption perceptions, an improvement from 164th when Conde won power in 2010.
Diallo said mining investors had been deterred by Conde's decision to hand the state a larger share of new projects.
"I would liberalize the mining sector while protecting the interest of Guineans," said Diallo, a trained economist. "There will be no investment if there are no profits for investors."
