The world\'s biggest platinum producer, Anglo American Platinum, sacked 12,000 striking workers in South Africa Friday, just hours after one miner was killed in clashes with police. Meanwhile a union leader in nearby Marikana was shot dead in the evening, his union said. \"A branch secretary of the union at Western Platinum was shot and killed at his house in Marikana this (Friday) evening,\" said National Union of Mineworkers spokesman Lesiba Seshoka in a statement. Anglo American Platinum said the miners failed to appear before disciplinary hearings \"and have therefore been dismissed in their absence\". It is the latest crisis to hit South Africa\'s vital minerals sector, which has been crippled by a wave of violent disputes over miners\' pay since August. Around 28,000 Amplats workers have been on strike for three weeks at the firm\'s sprawling facilities in the northern town of Rustenburg, which account for around a quarter of world platinum production. The company said the strike had so far cost 700 million rand ($80 million, 60 million euro) in lost revenue. In a bid to halt further losses, Amplats on Monday warned wildcat strikers that they would be sacked if they failed to attend hearings. It has now made good on that promise. \"Despite the company\'s repeated calls for employees to return to work, we have continued to experience attendance levels of less than 20 percent,\" Amplats said in a statement. Workers, some of whom received SMS messages from Amplats informing them of the news, reacted with a mixture of shock and defiance. \"If they fired us, no problem,\" said Claudio, aged 37, from Mozambique. \"We are going to market ourselves somewhere else.\" Others were more circumspect. \"Now what is going to happen?\" asked a worried 21-year-old miner from the eastern province of Mpumalanga, who had not gone to work because of the threat of violence from colleagues. But with many miners unwilling to give up their demands for higher pay and Amplats taking a tough line, the spectre of violence loomed. In August, 46 people died during a strike at the Lonmin platinum mine in nearby Marikana. \"Things now are tuning to a point,\" said Gaddhafi Mdoda a worker and activist, \"they are leaving us with no choice.\" At least six people have been killed around Rustenburg in strike-related violence this week. Late Thursday one miner was killed when police used tear gas and rubber bullets to disperse a group of 300 illegal strikers protesting on a hilltop close to the mines. The independent police watchdog is investigating the man\'s death \"as the incident appeared to have arisen from police action\", according to police spokeswoman Emelda Setlhako. \"The crowd began stoning the police who then had to use stun grenades, rubber bullets and tear gas to disperse them,\" spokesman Setlhako said in a statement. The victim has not been officially identified, but colleagues told AFP the man, in his late 40s, was from the rural Eastern Cape province and had been a rock drill operator at the Bleskop shaft. On Friday police cordoned off the hill with red tape as investigators examined the scene, while strikers barricaded roads close by with tyres and rocks. \"The situation is tense,\" said local police spokesman Thulani Ngubane. With around 100,000 workers currently on strike across the country, President Jacob Zuma -- who has publically kept his distance from the crisis -- on Thursday called for the work stoppages to end. Speaking to business leaders in Johannesburg, he warned the strikes would hurt South Africa\'s ability to attract more investment and growth. \"We should not seek to portray ourselves as a nation that is perpetually fighting.\" Investors, already spooked by earlier violence, warned Friday\'s dismissals could deepen a crisis that has already paralysed an industry that accounts for around 20 of South Africa\'s GDP. \"The government is doing nothing,\" said Peter Attard Montalto, a strategist with Japanese bank Nomura, who warned the strikes had already shaved 0.2 to 0.3 percent off third quarter growth. The South African rand sank against the dollar on news of renewed violence. Analysts have warned that the strikers\' demands will result in job losses in the country where one in every four employable people is already out of work. Amplats will hope Friday\'s high-stakes gambit gives them the leverage needed to end the unrest. In February, Amplats\' rival Impala Platinum fired 17,000 workers, only to rehire them a few weeks later as part of a wage agreement. Amplats on Friday indicated it was open to \"exploring the possibility of bringing forward wage negotiations within our current agreements\".