South African police fired rubber bullets, stun grenades and tear gas on Saturday to disperse a protest by striking miners accusing union leaders of betraying worker interests. Bullet casings littered the ground and a helicopter circled, with police sirens howling, outside a stadium in northwestern Rustenburg in the latest strike unrest that has rocked the key mining sector for weeks. The violence erupted as the Congress of South African Trade Unions (Cosatu), the country\'s largest labour umbrella, marched to the venue for a rally in a bid to regain its authority, which has been dealt a heavy blow since the mining unrest began in August. \"Police had to use the stun grenades and rubber bullets at the stadium to disperse the crowd,\" Colonel Emelda Setlhako told AFP, saying about 400 protesters had tried to disrupt the meeting. \"Only one person was slightly injured and seven have been arrested for unlawful gathering.\" The injured person had been beaten up in clashes, she said, with an AFP photographer seeing a man, dressed in the labour grouping\'s trademark red, bleeding after he was assaulted. The strikers are unhappy with the way the National Union of Mineworkers, Cosatu\'s biggest affiliate, has been representing their interests and have snubbed the labour giant in a wave of illegal, deadly strikes. \"They take their own decisions by themselves, they don\'t consult with the workers. And they are there to represent us, the workers,\" said Anglo American Platinum (Amplats) worker miner Simon Mothlabi about the NUM. \"They\'ve been earning a lot of money, like management, and us workers, we are just earning peanuts.\" The Cosatu grouping is a key ally of the ruling African National Congress and some of its former union leaders now hold key positions in business, government and the party. It accuses organisers of the wildcat strikes, which saw police gun down 34 people in August, of having a political agenda and causing mass job dismissals. \"South Africa is sitting on a time bomb when it comes to unemployment,\" Cosatu general secretary Zwelinzima Vavi told journalists after addressing about 1,500 people. A memorandum demanding the reinstatement of fired workers and the opening of pay negotiations was handed to government officials at the rally. Nearly 60 people have been killed since August, including 34 shot dead by police at Lonmin\'s Marikana mine. Saturday\'s unrest came a day after the NUM announced that it had reached a deal with Amplats, the world\'s number one platinum producer, to rehire 12,000 fired workers after six weeks of strikes at its mines. The global miner on Saturday said it has given workers until Tuesday to return and will offer a 2,000 rand ($179 or 231 euros) allowance if they do so. The offer did not change the current wage agreement, it said. But striking workers said they were not aware of the deal, which would signal a further winding down of the strikes that have rocked platinum and gold mines. \"We know nothing about it. We were not consulted, we only heard about it on the radio,\" said Amplats worker Reuben Lerebolo, carrying a poster stating \"NUM we are tired of you\". \"We can\'t go to work until our demands are met,\" he said. The moves to end the strike at Amplats comes as a strike in the gold mining sector also neared an end following a pay agreement. The unrest has cost 10.1 billion rand ($1.2 billion, 912 million euros) in lost production this year, pushing the country\'s yearly growth forecast downward to 2.5 percent. The industry contributes up to nearly one fifth of GDP when related activities are included.