JOHANNESBURG - Twenty illegal miners are feared to be killed by a rockfall in a closed gold mine in the eastern South African province of Gaudeng, local media reported on Thursday evening.

A survivor from the rockfall said 20 other miners trapped were killed in the Gravelotte Mine on the East Rand, which lies 20 km east of Johannesburg in Gaudeng.  

The incident occurred on Monday as a group of illegal miners blasted rock with explosives. Police said those miners underground were pinned down by a rock with a size of a house, measuring about 40 meters by 30 meters by 1.4 meters.

Three members of the group had been injured on the scene, and two of them sustained fatal injures.  

The number of the miners killed in the accident had not been confirmed, because local relief workers failed to recover the bodies due to unstable conditions.

The Gravelotte Mine has witnessed many miners death related to unsafe mining conditions and battles between illegal miners and security forces in recent years.

About 20 illegal miners were killed in August, 2010, while three illegal miners were dead last year.