AngloGold Ashanti , Africa's biggest gold producer, said on Thursday that a worker was killed at its Mponeng mine in South Africa after a seismic event, bringing mining operations to a halt in the affected area.

"A seismic event just after 1am triggered a fall of ground, killing a winch operator and injuring his team leader ... The team leader is in a stable condition in hospital," spokesman Alan Fine said in an e-mail.

This brings to 75 the number of workers who have been killed in South Africa's mines so far this year, a spokesman for the National Union of Mineworkers said.

South Africa's mines are among the most dangerous on earth and Mponeng is the world's deepest mine, reaching depths of close to 4 kms (2-1/2 miles) below the surface.