South Africa's Competition Commission on Wednesday announced the uncovering of an alleged mining-supply cartel.

The findings of the commission have been referred to the Competition Tribunal, which has been asked to levy a penalty of 10% on the annual turnover of three of the four firms named.

The four are Aveng Africa's Duraset; RSC Ekusasa Mining; Dywidag-Systems International; and Videx Wire Products.

All supply mining roof bolts, which are used to prevent cave-ins in underground mines.

RSC, a subsidiary of Murray & Roberts Steel - which is part of the JSE-listed Murray & Roberts group - was the first to admit it had colluded with its competitors, and submitted a leniency application on September 26, 2008.

Subsequently, another unnamed party's attempt to apply for leniency was turned down.

The cartel, which is believed to have started in the 1990s, was resuscitated in 2002 when DSI entered the market with prices its competitors considered as "exceptionally low and unsustainable".

After a price war, the respondents eventually agreed not to sell to "each other's mines" and each member was allocated 25% of market share.

The members had agreements to allocate customers and products and also to collude on tenders.

De Beers, Gold Fields, Harmony, Anglo Platinum, Lonmin and Sasol Mining were among the mining houses that bought roof bolts from the companies.

The commission is a Competition Act body that is empowered to investigate restrictive business practices and abuse of dominant positions.