Mercedes-Benz UK and three of its dealers have been fined GBP2.6m over price-fixing by the government's Office of Fair Trading over breaches of competition law in the trucking industry.

According to the Daily Telegraph, Mercedes' UK arm and all three dealers - Ciceley, Road Range and Enza - admitted to "some element" of market sharing, price fixing or "exchange of commercially sensitive information" relating to the distribution of commercial vehicles between 2008 and 2010.

The fines concluded a three-year investigation by the OFT which saw the managing director of Mercedes-Benz's commercial vehicle wing arrested when the consumer regulator raided the automaker's UK offices in Tongwell, Milton Keynes. He was released on bail on the same day.

Mercedes UK and parent Daimler were ordered to pay GBP1.5m while the dealerships, based in Northern England and parts of Scotland and Wales, were levied fines running to the hundreds of thousands, the paper said.

A fourth dealer, Northside, also admitted involvement but avoided a penalty under immunity granted after it was the first party to provide evidence to the OFT.

Without a 15% discount for cooperation with the regulator, the total penalty would have reached £3.07m, the report said.

"These cases send a clear signal that the OFT will take firm action against companies that collude to deny customers the benefit of fair competition regardless of the size of the firms involved or geographic scope of the investigation," said Ali Nikpay, senior director of cartels at the OFT.

He added that the OFT had to uncover the cartel without a tip off from a whistle blower.

A Mercedes-Benz spokesman told the Telegraph the company had responded to the investigation by "strengthening its internal controls" with "every member of staff participating in comprehensive and ongoing integrity training programmes."

"Mercedes-Benz takes its responsibilities under competition law seriously and has taken all appropriate steps to ensure all its staff comply fully with the law," he added.

Cartels are illegal in the UK because they are seen as highly damaging to consumers, potentially costing them substantial amounts of money from the lack of competition.