Security forces shot dead at least 20 people on Monday as tens of thousands of Guineans turned out to demonstrate against President Lansana Conte in the biggest nationwide show of discontent in his 23-year rule.

In the capital, Conakry, violent clashes between protestors and the Guinean army were reported in most of the sprawling city’s suburbs, with protestors “pouring” into main city streets from as far as 20km outside the city centre, witnesses said. Eleven corpses with gunshot wounds were admitted to one city morgue, and six others to morgues elsewhere, hospital staff told IRIN. Three other people were reported killed in the often violent suburb of Hambaleye.

In the far-eastern town of Kankan, observers estimated that 20,000 people began marching in the morning, but three hours of violence ensued after the army started shooting into the unarmed and largely peaceful crowd. At least three people were critically injured, but casualties could not be confirmed as shooting was still ongoing, residents said.

In Kissidougou, local residents also reported a peaceful demonstration in the morning, which by mid-afternoon had been broken up by the army. Residents said soldiers were chasing unarmed protestors through the town streets and shooting into crowds.

Demonstrations and shooting by the army were also reported in the towns of Labe, Pita, and Dabola. The restive southeastern city of Nzerekore, where residents say three people were shot and at least 21 wounded in protests over the weekend, remained calm on Monday.

“These were huge crowds and it wasn’t like other days when it was more like gangs. This time it was normal families, women, teenagers, heads of family marching. It was a vast crowd,” a resident in Kankan said.

“There were different groups around the city that started marching towards the government buildings,” he said. “Then the military came and started shooting randomly. There were bullets going everywhere.”

Guinea is now in the 13th day of an “indefinite” strike called by the country’s powerful trade unions to protest the rising cost of living, which they say is caused by economic mismanagement and corruption at the highest levels of government.

Leaders of the trade unions behind the strike warned on Monday afternoon that they have “lost control” of the movement.

“The unions cannot control certain movements organised by associations that we do not know about,” Boubacar Biro Barry, negotiator for the trade unions, told IRIN.

Several youth members of the Guinean Workers Union (USTG) and the National Confederation of Guinean Workers (CNTG) were arrested on Monday afternoon, and the union headquarters was sacked by an army unit led by President Conte’s son, Army Capt. Ousmane Conte, union staff told IRIN.

Union leaders, who were last week threatened by Conte in an acrimonious meeting that failed to end the strike, could not be reached for comment on Monday afternoon, but Barry said talks with the government are “on hold” until the army stops shooting protestors.

The unions have accused septuagenarian President Conte, a former army colonel who seized power in a coup in 1984, of being too ill to manage the country, and called on him to retire his government and hand over all his powers to a new prime minister.

Conte has refused to relinquish his powers, but has resigned the country’s current prime minister and offered some concessions to the strike-leaders.

On Friday, West African heads of state at a meeting of the regional ECOWAS grouping called for calm, and proposed sending a high-level delegation to Conakry to meet President Conte.