A major household fuel supplier based in Sheffield insists it has cleaned up its act, after agreeing to pay a £2.8 million fine for trying to rig prices.
CPL, which has its headquarter in Killamarsh, conspired with rival firm Fuel Express to form an illegal market-sharing cartel.
The two firms, which provide coal and fuel logs for household fires, admitted breaking competition law by rigging competitive tenders to supply Tesco and Sainsbury's.
For each of the tenders, they agreed that one would submit a higher bid which was designed to lose - so the existing supplier could retain 'its' customer.
The racket was exposed following an investigation by the Competition and Markets Authority (CMA), which carried out unannounced inspections at both firms' premises after receiving a top-off to its cartels hotline.
The probe revealed the companies had engaged in this illegal market-sharing arrangement from June 2010 to February 2011.
CPL agreed to pay a £2.8m fine and Fuel Express accepted a penalty of £628,000, with both sums reduced by 20 per cent because the companies admitted the offence and cooperated with the watchdog.
Stephen Blake, CMA's senior director for cartels, said: "Millions of people buy these products to help keep their homes warm in winter and to fire up their barbecues in summer, so it’s important that shoppers are offered the best price. This will only happen when companies compete fairly.
"Market sharing and bid rigging are illegal. They skew the market so businesses don’t have to compete for customers, who in turn are cheated out of a fair deal and can end up paying higher prices or having to make do with poorer quality products or services.
"Today’s announcement shows how seriously we take this type of activity. It’s important that all businesses play by the rules and the CMA will pursue those who break the law."
CPL said it had put in place a series of measures since the offence to ensure it upholds the 'highest standards' of business practice.
A spokeswoman for the firm said: "The board of CPL is committed to compliance with Competition Law and has acted in full cooperation with the Competition and Markets Authority’s investigation.
"The settlement relates to specific behaviour that took place between June 2010 and February 2011.
"Since then, CPL has introduced a series of additional measures to ensure the highest standards of business practice are upheld.
"This includes detailed compliance training, roll-out of a formal Code of Conduct and the introduction of a Senior Executive Compliance Group. A whistle-blowing helpline is also being launched."
* The CMA's dedicated hotline for reporting cartels is 020 3738 6888.