This resulted in a confrontation between the two unions on a road near the mine Monday. During that standoff, an AMCU member was also killed in an apparent retaliation. Bringing the situation to a boil-over that prompted Northam Platinum to temporarily suspend operations at the mine for fear of further violence. As Northam Chief Executive Officer Paul Dunne told local radio Tuesday: "We have halted underground operations for the moment until we are sure that full calm returns. We have a very significant police presence on the mine." As of right now, there's no word on the underlying cause of the disputes. Although there's been a lot of bad blood the last few years between the NMU and the AMCU - with the latter union growing rapidly, and taking members from the NMU, which was formerly South Africa's largest mineworkers group. Related: Aviation Giants To Ramp Up Biofuels Usage Whatever the case, it's notable that labour issues are now having a concrete impact on production.