Thousands of people have answered a call by the main opposition party in Guinea to march in the capital, Conarky, to protest against February's disputed local election.
Union of Democratic Forces of Guinea (UFDG) called for the city to come to a "standstill".
Youths erected roadblocks and set fire to tyres in an expression of anger against President Alpha Conde.
The march coincided with growing calls for authorities to reopen schools following a teachers' strike on 12 February.
AFP reports that several hundred demonstrators gathered outside the presidential palace, chanting anti-Conde slogans and demanding an end to the school strike.
"How can we accept the silence and contempt of the president when our children have been at home for a month?" a woman is quoted as saying.
Protests erupted after local elections on 4 February, which were won by the ruling the Rally for the Guinean People.
The elections were the country's first at a local level since 2005.
AFP reports that around 12 people have died in the unrest, some of whom were shot dead by police.
