More than 2,200 platinum miners on Monday launched the fourth underground protest to hit South Africa's crucial mining industry in two months.
Operations were suspended in two shafts at the Bafokeng Rasimone mine, northwest of Johannesburg, because of what the owners called an "illegal underground protest".
Impala Platinum Holdings, one of the world's key platinum producers, also known as Implats, said 2,205 miners had joined the protest.
It said in a statement the reasons for the protest were "still to be determined" and that it was "closely monitoring" events.
Implats said it had "proactively suspended mining operations at the two shafts and recalled all employees from the underground working areas."
Authorities have been informed to "safeguard" the miners underground, Implats said.
The company warned it will "address those employees who engage in illegal conduct and criminal acts in a decisive way".
South Africa has seen a growing number wildcat strikes by miners who occupy the mines, blocking production.
"Illegal underground protests and copycat illegal actions ... have become more prevalent in recent months and are a cause for both considerable concern for and disruption to the broader mining industry," Implats said.
More than 100 gold miners spent nearly three days underground in Springs near Johannesburg in October as part of a dispute between rival unions.
Another 440 staged a protest in another gold mine this month while 250 platinum workers demanding better wages occupied a shaft for three days at the same time.
Mining employs hundreds of thousands of people in South Africa -- the biggest exporter of platinum and a major exporter of gold, diamonds, coal and other raw materials.