The energy department announced that the petrol price will decrease by 45 cents a litre on Wednesday.
The currency firmed slightly after data showed the domestic trade deficit narrowed to R2.91 billion.
The minister says the SIU has been called in to investigate allegations of maladministration.
The group is believed to be responsible for at least three fires at the mine this month.
Lesetja Kganyago says there are rigidities in SA's labour market.
As of Wednesday the diesel price will go down between 60 and 61 cents a litre.