The Association of Mineworkers and Construction Union (AMCU) said Sunday in a statement that five workers had died at the Palabora Mining Company's copper mine in South Africa's Limpopo province after a fire broke out underground.

According to AMCU, mineworkers were asked to evacuate the mine after smoke was seen by a logistics belt operator.

The union said the mine's proto team had not been ready to complete a rescue, with another called in from the Burgersfort area, delaying rescue efforts, which were in turn hindered by high temperatures.

It said one mineworker remained trapped underground Sunday evening and one was recovering in hospital, while minister of mineral resources Gwede Mantashe tweeted Monday that six mineworkers had passed away.

"It is unfortunate that yet again, as a country, we have lost so many lives in this disaster. These deaths add to an already high number of lost lives in the industry since the beginning of the year," he said.

There have now been over 50 deaths in the mining industry since the beginning of 2018, making it the second worst year so far this decade after 112 people died in 2012.

Mantashe called on mining companies to prioritise the safety of mineworkers at all times and said there would be an investigations into the incident once the area was declared safe.

Unions also called for mining companies to put the lives of mineworkers first to achieve zero harm or deaths in the industry and to be held accountable for the deaths of mineworkers.

The National Union of Mineworkers "vehemently" condemned the incident, noting that "the fact that there is no improvement on fatal accidents in the mining sector can only be interpreted as a sign of a lack of commitment towards zero harm and zero death by the mining sector".

"We further urge the department of mineral resources, which is the regulator, to play its role in ensuring that mines are safe and put the safety of the mineworkers as a priority," it said.