The Office of Fair Trading investigation into alleged price-fixing by the four major supermarkets has been expanded to target several leading household brands, according to a report.
The Daily Telegraph claims to have seen a document that names Procter & Gamble, Coca-Cola, GlaxoSmithKline, Unilever and Andrex's US owner Kimberly-Clark as companies under investigation.
Familiar brands such as Andrex toilet paper, Anadin Extra, Cadbury Highlights and Warburtons bread are among items on the list, the newspaper said.
The four major supermarkets Asda, Morrisons, Sainsbury's and Tesco were all raided last week as part of a probe into possible price fixing on hundreds of goods.
The firms involved have confirmed they have received visits, but have not given any details as to what the OFT was looking for.
Procter & Gamble said in a statement: "We can confirm that Procter & Gamble were visited by the OFT on Thursday. Consistent with our principles, we are fully co-operating with their inquiries.
"We do not have any additional information to share at this stage, save to say that it is Procter & Gamble's policy to fully abide by the spirit and letter of the law."
A GlaxoSmithKline spokesperson said: "We have received a letter from the OFT in relation to the OFT's competition enquiry and we will respond in due course."
A spokesperson from Unilever said: "We can confirm that we have been approached by the OFT with a section 26 request for information and that we are in the process of responding."
The OFT has also recently launched an investigation into the price fixing of tobacco products sold in supermarkets and bid rigging in the construction industry.