Emergency workers Sunday were striving to rescue illegal miners trapped underground in Johannesburg's oldest gold mine, a spokesman said.

The diggers -- whose numbers are unclear -- are said to have been trapped in the disused mine since Wednesday.

Only four have so far been brought to surface while others are believed to have died.

‘We were called to the scene on Thursday, but other reports suggest that the people have been trapped since Wednesday,’ said Johannesburg Emergency Services spokesman Synock Matobako.

‘We don't know exactly how many people are underground, we have been informed that they could be up to 16.’

The mine in Langlaagte is where gold was first discovered in the city in 1886.

Matobako said the mine was abandoned many years ago when its owners ceased operating.

‘The rescue mission is slowed by the difficult and dangerous conditions underground, as the mine is very old. We have to walk and crawl in small tunnels for about 1.5 kilometres to reach some of them,’ he said.

Rescued diggers were treated by medics before being arrested by police.

The Mines Rescue Services said its teams were being guided to a scene underground where seven suspected fatalities were said to be located.

‘After two and a half hours of walking, our members are now close to the area where the seven bodies are said to be lying,’ Mines Rescue Services boss Christo de Klerk told journalists.

Areas around Johannesburg are dotted by disused gold mines, attracting thousands of illegal miners who descend into the old shafts, sometimes living for months underground digging for nuggets.

In most cases illegal diggers die underground or get killed by rival group who compete for the meagre pieces of precious metal, which is then sold on the black market.