More than 60 people have also been wounded as security forces proved unable to prevent the fighting spreading.
The bloodshed initially broke out in the southern forest region early yesterday when petrol station guards from the Guerze tribe in the town of Koule accused a young ethnic Konianke male of stealing.
The youth was subsequently tortured and beaten to death.
Fighting has now spread to the nearby provincial capital N'Zerekore, 570 kilometres southeast of Conakry, leaving several homes destroyed.
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Lamah said hospital workers had not yet begun to establish an accurate death toll, as so many had been killed.
"Some were burned alive while others were cut with machetes. We are not able to manage. This situation is beyond us," he added.
A state radio correspondent in N'Zerekore said it was unlikely that an accurate death toll would be established as the bodies of many attacked by machetes had not been sent to hospital.
A security source said the government had dispatched two of its top army colonels -- the director of the national organised crime agency and the head of President Alpha Conde's security -- to restore order.
The men come from the region and are members of the two opposing tribes.
A number of witnesses told AFP Guerzes and Koniankes were attacking one another with machetes, axes, sticks, stones and firearms, setting fire to houses and cars.
"The Konianke protesters also set fire to his home and his car," he added.
Communal violence is common in the region, near the border with Liberia, where clashes between the two tribes regularly break out over religious and other grievances.