South Africa's Northam Platinum suspended production at its Zondereinde mine after a worker was stabbed to death there during a fight between members of two different unions, the company said on Monday.
Northam said the fight broke out after another worker had been shot dead in a nearby town on Sunday.
The mine produces about 300,000 ounces of platinum a year, according to Northam's website. It was not immediately clear when production would resume.
The platinum belt - in which the Zondereinde mine is located - has been the battlefield for a membership turf war between the National Union of Mineworkers (NUM) and the Association of Mineworkers and Construction Union (AMCU).
NUM officials said the employee killed on Sunday was a member of their union. An AMCU official said the worker killed on Monday belonged to the union.
The NUM represents a majority of the worker's at the mine.
Police were not immediately available to comment.
AMCU President Joseph Mathunjwa told Reuters, "the situation is tense, its not as normal as one would hope".
NUM official Ecliff Tantsi said members of his union did not turn up to work on Monday and that it would meet with Northam officials later in the day.