Over 200 workers were feared trapped Sunday inside an illegal gold mine in South Africa, emergency rescuers said.
"We have got communication with about 30 trapped miners. They have told us that underneath them there's 200 others," Werner Vermaak spokesman of private emergency operators ER24 told AFP.
But he said he could not independently confirm the figure of 200 while local municipality officials could only confirm 30 trapped.
The workers went down on Saturday into the mine, which has been dug illegally behind a cricket stadium in the Benoni district east of Johannesburg.
They failed to come out after a boulder fell and blocked their way, municipal rescuers said.
"We are currently in the process of attempting to rescue them," Roggers Mamaila of the Ekurhuleni municipality emergency services told AFP.
Heavy duty excavation equipment has been brought in to help in the rescue operation.
But Vermaak said it was "very dificult to access them at this moment".
Police on patrol had discovered the men when a passer-by said he had heard voices of people screaming from underground.
Accidents are commonplace in South Africa's mines, which are the deepest in the world.
At least eight miners were killed nearly two weeks ago after an earth tremor sparked an underground blaze at a Harmony Gold mine west of Johannesburg.
In July 2009, nine workers were killed in a rock fall in a platinum mine.
The same year, at least 82 people digging illegally in an disused gold mine shaft died when a fire broke out underground.