The company which owns the prospecting rights to the abandoned mine in which at least 30 "illegal miners" were trapped says heavy rain may have been a trigger for the shaft's collapse.
Chinese-owned bullion producer Gold One owns the prospecting rights to the abandoned gold shaft, however was not currently working in it.
"The illegal miners have dug a tunnel right next to it to access the shaft and it has collapsed behind them," Gold One spokesman Grant Stuart said.
Emergency services in South Africa have been using a crane to shift a large concrete slab obstructing the shaft.
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