A sixth miner has died after Sunday's accident at a copper mine in South Africa's northern Limpopo province.

Reports says a conveyor belt caught fire.

Miners were then instructed to evacuate to the closest refuge chamber as temperatures "rose to [between] 64 and 67 degrees Celsius, [which] made the rescue efforts impossible," news site IOL quotes a statement from the Associated Mineworkers and Construction Union (Amcu).

There were 200 workers underground at the mine, owned by the Phalaborwa Mining Company, when the fire broke out, most of whom were safely brought to the surface.

Some of them have been receiving treatment in nearby hospitals. The mine is in the northern Limpopo province, one of the poorest areas in South Africa.

The National Union of Mineworkers (Num) called mine companies to put lives ahead of profits.

In a statement it said: "As the Num, we vehemently condemn this kind of incident as there is a high number of fatalities in the mining industry in South Africa this year."

"We call upon employers to put lives of mineworkers first so that we can be able to achieve zero harm and zero death in the mining industry.”

Mineral Resources Minister Gwede Mantashe sent condolence messages to the families of miners who died.