The suit was launched almost six years ago on behalf of miners suffering from silicosis, a fatal lung disease contacted by inhaling silica dust in gold mines.

Almost all of the claimants are black miners from South Africa and neighbouring countries such as Lesotho, whom critics say were not provided with adequate protection during and even after apartheid rule ended in 1994.

"The faster we settle, the faster we can pay compensation to those who are entitled to it," Graham Briggs, chair of the Working Group on Occupational Lung Disease, told Reuters ahead of a presentation on the topic he was to give at a mining conference in Cape Town.

The six companies involved are Harmony Gold, Gold Fields, African Rainbow Minerals, Sibanye-Stillwater, AngloGold Ashanti and Anglo American.

Anglo American no longer has gold assets but historically was a bullion producer.

The six companies said late last year they were making provisions for about 5 billion rand and Briggs said there was close to 4 billion rand in a compensation fund which companies have been contributing to for years.