A list of grocery products running to five sheets of A4 paper includes Andrex toilet paper, Anadin Extra, Cadbury Highlights and Warburtons bread, according to the Daily Telegraph.
The OFT made a surprise visit to the head offices of Asda and Morrisons last week, while Sainsbury's and Tesco have also been asked for information.
Suppliers Coca-Cola Enterprises, Britvic, Nestlé, Mars and Reckitt Benckiser have also been asked to provide information to the OFT, according to the Financial Times. The Daily Telegraph also lists Procter & Gamble, GlaxoSmithKline, Unilever and Kimberley-Clark.
Meanwhile, former Asda CEO Archie Norman has attacked the OFT's recent investigations on the grocery sector which include milk and tobacco.
“Does it make sense for the OFT to be devoting such a large amount of its time to achieve technical results? No, it does not,” he told The Times.
“There are plenty of other areas where the OFT could be spending its time. We have one of the most competitive food industries in the world - they are beating the guts out of each other every day,” he added.