Angloplat says that the ongoing strike action at its platinum mining operations is starting to have an impact on output.

The world's biggest producer of platinum said that it had started to see the effects of the stoppage already, although it maintained that less than half of workers were involved in the strike.

Angloplat spokesman Mike Mtakati told Reuters that only 30-40 per cent of the workforce was involved in the strike.

"The strike is now having an effect on production, but one cannot quantify how much at this stage [. . .] some of the mines are operating at 100 per cent, some at 70, some at 80 per cent," he said.

Mr Mtakati said that a number of precious metals and base metals refineries had continued to operate with non-unionised staff but comments from National Union of Mineworkers (NUM) deputy general secretary Archie Palane suggest that this may not last.

Mr Palane said that the number of workers on strike had now risen from 17,000 to nearer 20,000 and claimed that further participants were expected.

"As we consolidate with other workers who are non-NUM members, the numbers will go higher," he said.