South Africa's Hernic Ferrochrome, a unit of Japan's Mitsubishi Corporation, said on Tuesday it was unaffected by a wage dispute between a union and one of its contractors.

The National Union of Mineworkers said earlier on Tuesday that over 500 workers had downed tools at Hernic Ferrochrome's mine in a wage dispute, but a spokesman for the company disputed that.

He said the dispute was between the union and contractor Hydro Sebenza and concerned just around 129 employees out of Hernic's total number of contractors of around 2,300.

Hydro Sebenza declined to comment.

Africa's biggest economy has been hit by a wave of strikes and strike threats in both the private and public sector, which have led to above-inflation settlements and stoked fears that the cost of living will rise.

The deals, some of which were double the inflation rate, led to the finance ministry saying they posed a risk to the economy.