Companies involved in price-fixing rings can avoid hefty fines if they blow the whistle on their fellow conspirators.
Officials at the OFT have now launched new leniency guidelines outlining easier ways for firms to get in touch and detailing how they will be exempt from massive fines and criminal prosecutions.
Simon Williams, OFT senior director of cartels and criminal enforcement, said: "Cartels cheat consumers by restricting competition.
"The leniency programme continues to be a simple and powerful tool to expose such conduct and the revisions to the OFT's guidance will help ensure that the programme continues to provide a powerful incentive to seek leniency before it is too late."
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