Time is running out to save the three mine workers trapped in a South African gold mine since Friday, the mining union's president has warned.

Joseph Mathunjwa spent the night underground with the rescue team.

The three were working above ground in the lamproom when a building collapsed into the mine, burying them under tonnes of rubble.

More than 70 miners managed to escape using an emergency exit.

The rescue team says they have got a response to tapping sounds that they made from above.

"The longer they remain trapped the slimmer the chances of them being found alive," the president of the Association of Mineworkers and Construction Union (AMCU), Mr Mathunjwa said on the union's website.

The statement added that the rescue team were able to break the rock that was blocking the entrance to the container room where the miners are trapped and are currently removing tonnes of rubble.

Rescuers had previously heard tapping, giving hope that the three were still alive in the Lily Gold Mine in Barberton, South Africa.

But the AMCU's regional secretary John Sibiya told South Africa's Times that the rescuers have not heard anything from the trapped workers for 20 hours.