The accident happened in a mine run by informal workers in Kintinia, about 800 km (500 miles) northeast of Conakry, an area which holds some of the West African country's largest gold reserves.

"They were artisanal miners who took up work in a structure that had been closed," Cheick Diallo, the prefect for Siguiri province told Reuters. "We have counted 13 bodies since the collapse a few days ago."

Informal mining in mineral-rich Guinea is extremely dangerous and accidents and suffocation in the narrow, fragile shafts are frequent.