At least five workers have been shot after security guards at an Anglo American Platinum mine near Rustenburg allegedly opened fire.
It followed clashes between rival union factions, eNews Channel Africa television said.
The station said it believed one worker at the Siphumelele shaft had been killed.
Union and company officials were not immediately available for comment.
Anglo American Platinum, or Amplats, in January raised the ire of labour and the government when it said it planned to mothball two South African mines, sell another and cut 14 000 jobs.
The world's largest platinum producer was hit by violent strikes last year, sparked in large part by a turf battle between rivals unions for membership.
Amplats shares were down more than 5% in afternoon trade. – Reuters.