The Office of Fair Trading (OFT) is investigating allegations of price-fixing at some of Britain's largest dairy operations.Investigators have searched a number of premises in northern England as part of a wide-reaching operation, with many suggesting market sharing has been occurring.

An OFT spokesman told the Times newspaper that sites operated by major players including Arla Foods, Express Dairies and the Co-op were visited.

Arla Foods group director Kim Nielsen said: "The company has nothing to hide and will therefore cooperate fully with the investigation."

This investigation is separate to the investigation being undertaken by the Competition Commission, which is looking to see if the merger between Arla Foods and Express Dairies is in the public interest.

The Competition Commission will make its recommendation towards the end of September this year.