The UK’s four biggest grocers are under investigation by the Office of Fair Trading (OFT) for allegedly fixing prices of health, beauty and grocery products.

The OFT is understood to have made visits to the head offices of Tesco, Asda, Sainsbury’s and Morrisons and to some of their suppliers. The supermarkets are understood to be co-operating with the investigation.

Tesco said in a statement: “We understand that the OFT has asked for information from a wide range of suppliers and retailers. We are working with them to provide what they require. At Tesco we are confident that we always act in the interest of consumers.”

The move comes just days after the OFT announced it was looking into allegations that 11 retailers, including Asda, Sainsbury’s and Tesco, and manufacturers were working together to fix cigarette prices.

Last week the OFT was forced to apologise to Morrisons after wrongly claiming that the grocer had colluded with other supermarkets and dairy producers to push up the price of butter and cheese in 2002 and 2003. It paid out£100,000 in damages.