Supermarkets and dairy companies have said they will fight allegations that they colluded to increase the price of dairy products.

Yesterday, the Office of Fair Trading provisionally found that Asda, Morrisons, Safeway, Sainsbury's and Tesco, as well as Arla, Dairy Crest, Lactalis McLelland, The Cheese Company and Wiseman, “colluded to increase the prices of dairy products” between 2002 and 2003. Consumers lost an estimated £270m, it claimed.

The companies said they would examine the report and defend themselves against the claims.

Analysts said that although there could be some sizeable fines, these would be nothing more than an irritant for the supermarkets.