Impala Platinum (IMPJ.J) said on Tuesday it had temporarily halted operations at its Rustenburg mining complex in South Africa after 11 workers died in an incident at one of its underground shafts.

The Johannesburg-based platinum miner said in a statement that 86 workers were involved in the incident at its No. 11 shaft and 75 injured workers had been admitted at four hospitals in the area.

The company said all mining operations at the sprawling Rustenburg complex in South Africa's North West province had been suspended on Tuesday.

"Today is the darkest day in the history of Impala and our hearts are heavy for the lives lost and the individuals affected by this devastating incident," CEO Nico Muller said in the statement.

Impala is among South African platinum producers that operate some of the deepest and oldest mining shafts in the world.

The suspension could be extended to Wednesday to allow the company to "mourn and heal emotionally", a company spokesperson said.

He could not immediately say how Impala's output would be impacted by the work stoppage.

"It's impossible to quantify the impact on production save to say 11 shaft on its own is a very large complex and contributes roughly 15% of Impala Rustenburg’s production and to the extent that it's stopped for any length of time, it will have a corresponding impact on their entire impact," the spokesperson said.

South Africa recorded 27 fatal mine accidents by September this year, according to the National Union of Mineworkers (NUM). The country registered 49 mineworker deaths in 2022, its safest year on record.