Harmony Gold’s Kusasalethu mine west of Johannesburg has been hit by a wildcat strike triggered by the sacking of six leaders of the Association of Mineworkers and Construction Union (AMCU) for their role in a violent stoppage earlier this year, a spokeswoman said on Monday.

Kusasalethu, which employs about 4 500 workers, has been a flash point for labour violence and strikes in recent years, threatening the viability of the mine and underlining the social risks of mining in South Africa.

Spokeswoman Marian van der Walt said the strike began on Friday and only a fraction of the workforce had shown up for work on Monday.

The National Union of Mineworkers (NUM) said in a statement that four of its members at the mine had their houses and cars torched on Saturday night and were being intimidated from reporting for work – a pattern that has unfolded before.

“This intimidation against members of the NUM has been happening for some time now and our members have reached a stage where they cannot tolerate it anymore,” NUM said. AMCU officials could not immediately be reached for comment.

Peter Steenkamp, CEO, Harmony said, “We appeal to employees to return to work and strongly condemn any act of violence or intimidation. It is important that discipline at the mine be restored to ensure the sustainability of the mine.”

NUM and AMCU have been waging an often violent turf war for years that has seen dozens of miners killed.

Kusasalethu last year produced 141 000 ounces, about 13% of Harmony’s total production of just over a million ounces.