(IDEX Online) - Diamond miners in South Africa are threatening to strike at De Beers and Petra after pay talks collapsed.The industrial action, announced on Friday, will also affect Exxaro, the biggest coal supplier to state-owned electricity company Eskom.De Beers has reportedly offered a 1.5 per cent increase in response to union demands for an eight per cent rise for all workers.William Mabapa, chief negotiator at the country's National Union of Mineworkers (NUM) said: "There is just no room for peanuts increases and for that, we are prepared for war," according to a Reuters news agency report.De Beers said it would continue negotiations. The NUM has yet to announce a date for strike action but has been granted permission after attempts at mediation failed.Pic courtesy De Beers