The Office of Fair Trading is investigating possible price collusion of health, beauty and grocery products at Tesco, Sainsbury's, Asda and Morrisons.

It made a surprise visit to the head offices of Asda and Morrisons last week, while Sainsbury's and Tesco had also been asked for information, according to the BBC.

The OFT has also requested information from suppliers Procter & Gamble, Unilever and Mars, while Reckitt Benckiser is also on a list of suppliers under scrutiny, according to the Financial Times.

“We have been asked for information about a number of suppliers and we are helping the OFT with its inquiries,” a Sainsbury's spokeswoman said.

Tesco added: “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.”

The investigation follows the release of a statement by the OFT on Friday which alleged 11 retailers, including the big four, and two tobacco manufacturers had engaged in unlawful practices in relation to retail prices for tobacco products.

What triggered this latest probe? There is a possibility that one supermarket has attempted to obtain leniency by co-operating with the OFT