The makers of some of Britain’s best known household brands are at the centre of a probe into alleged price fixing, it was revealed today.

Coca-Cola, PG Tips tea and Aquafresh toothpaste are among almost 100 products reported to be involved in the inquiry by the Office of Fair Trading. Manufacturers Procter & Gamble, GlaxoSmithKline, Kimberly-Clark, Unilever and Coca-Cola all confirmed they had received visits or letters from the competition watchdog.

Investigators have also visited a string of supermarkets, including Tesco, Asda, Sainsbury’s and Morrisons, reportedly seizing hundreds of e-mails which have been exchanged between the stores and suppliers.

The OFT refused to comment on the investigation today, but the organisation’s former director John Bridgeman said: “Supermarkets account for a huge amount of consumer expenditure.

“It is a £100 billion sector of the economy. There is no smoke without fire. The OFT is not going to go big on this unless it has something to go on.”Procter & Gamble, which lists Pampers among its top products, 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.”

Phil Thomson, spokesman for GlaxoSmithKline, said: “I can confirm that we have had a letter from the OFT, which we received last week. We will be responding to them in due course. I can confirm that it relates to Aquafresh.”

Unilever, Kimberly-Clark and Coca-Cola also confirmed they had been contacted by the OFT.

* Many of the big-name manufacturers were in Shropshire today for the start of Pro-Retail, a three-day trade show at Telford International Centre. It gives independent retailers a chance to meet potential suppliers.

By Carl Jones