A multi-million pound investigation by the Office of Fair Trading into price-fixing allegations in the supermarket sector has been axed.

The investigation is believed to have been one of the largest in the watchdog’s history, and the OFT closed it on “administrative” grounds.

The OFT raided several supermarkets and consumer goods companies in April 2008 after receiving information suggesting price-fixing. Grocers involved included Tesco, Asda, Sainsbury’s and Morrisons along with FMCG giants such as Procter & Gamble and Coca-Cola. The OFT can levy fines of up to 10% of annual sales on companies found guilty of price fixing.

The OFT said on its website that it had received “substantial evidence from more than one source” into “suspected indirect retail price co-ordination” between 2005 and 2008.

It said it reviewed material from several companies but decided not to proceed. It said: “The OFT… concluded that it was appropriate to close the investigation on administrative priorities grounds.”

The closure comes at a difficult time for the OFT, which is set to be merged with the Competition Commission next year. The supermarkets have long said that the UK grocery sector is one of the most competitive in the world, and does not need regulating.