More than 500 miners in South Africa have remained underground for over 36 hours in a standoff between rival labour unions, police and workers’ representatives said Tuesday.Management at the Gold One mine near Johannesburg and the National Union of Mineworkers (NUM), one of the two unions involved, said the miners were being “held hostage”.But the Association of Mineworkers and Construction Union (AMCU) denied it is keeping workers underground against their will, saying they are staging a “sit-in” protest instead.”About 567 NUM members are being held hostage by alleged AMCU members,” NUM spokesman Livhuwani Mammburu told AFP.The miners in Springs, east of Johannesburg, were supposed to return to the surface Monday morning after a night shift but failed to do so.They include almost 70 women, some aged over 60, Mammburu said. Late Tuesday afternoon, an AFP correspondent saw about 100 miners, mostly from the AMCU, singing protests songs as they awaited for the outcome of the meeting between the mine management and unions. Some told AFP they would be there all night, as police and security forces patrolled the scene. The dispute revolves around union representation at the mine, where NUM is currently the only group officially registered.The AMCU says an overwhelming majority of miners have signed up to join it. But it is yet to be given an official representation, and that it says is the reason for the protest.”Workers can only come out once they are given the organisational rights,” AMCU’s regional secretary Tladi Mokwena told AFP.Police spokeswoman Dimakatso Nevhuhulwi said officers were “on standby” and monitoring the situation while talks between the mine and the unions were ongoing.”The police can confirm that approximately 550 mine employees are reportedly held hostage underground at a mine in Springs since Sunday,” she added.NUM said the company sent medics and a security team with food supplies to the miners but they have also been kept underground. Industry group Minerals Council South Africa said there were “reports of nine people injured, and that food and medical supplies are not reaching people underground”.NUM was founded in 1982 by the country’s President Cyril Ramaphosa, a former labour unionist. It remains the nation’s biggest mineworker union.