Miners from a rival union are holding hundreds of colleagues underground in South Africa

A group of miners from an unregistered, rival union are holding hundreds of their colleagues underground for a second day at a gold mine in South Africa over a union dispute, police and mine officials said Tuesday . Some 15 miners have been injured in scuffles, the head of the mine said.

Details were sketchy and there were conflicting statements over what happened, with the unregistered union asserting it represents the majority of employees at the mine and it wants to be formally recognized. It said the workers underground were staging a protest and there was no hostage situation.

According to Jon Hericourt, CEO of New Kleinfontein Gold Mine company, which manages the mine, the incident erupted early Monday when miners from the AMCU union prevented hundreds of others from leaving after their night shift ended at the Modder East mine in Springs, east of Johannesburg.