South Africa's president is facing calls to order an inquiry into a police operation that was meant to combat illegal mining but ended up leaving 87 miners to die underground as authorities attempted to force them to surrender during a monthslong standoff.

The South African government has launched a rescue operation at an abandoned gold mine in the country’s North West province, where at least 109 men have died, a group representing the miners said, after local authorities cut off vital supplies in a dramatic bid to crack down on the country’s illegal mining trade.

South African police lowered a camera down more than a mile (1.5 km) underground into an illegal gold mine on Thursday to ascertain if any survivors or corpses were still there after a months-long siege by authorities in which at least 78 miners died.