Some of the UK’s best-known consumer brands face a probe over allegations into price-fixing, as the Office of Fair Trading (OFT) steps up its wide-ranging investigation into the grocery sector.

Last week, the OFT visited a number of leading supermarkets – including Tesco, Sainsbury’s, Asda and Morrisons – to investigate suspicions that retailers had conspired to fix their prices across a range of household products.

Now the investigation has widened to accommodate a list of about 100 consumer brands, including PG Tips, Coca Cola and Aquafresh, plus products such as Andrex toilet paper, Anadin Extra, Cadbury Highlights and Warburtons.

Investigators have apparently told the brand owners to supply detailed pricing information on a number of their products and, if they are found guilty, they face a potential fine of up to 10 per cent of annual sales.

Suppliers including Procter & Gamble, Coca Cola, GlaxoSmithKline, Unilever and Andrex owner Kimberly-Clark have until June to provide the OFT with the information that it has requested.

The move also follows separate investigations conducted on the price of dairy products and cigarettes.