The move is embarrassing for the country's largest retailer and has been hailed as a victory by its smaller rival Asda. It has also been proof of the power of social media sites, such as Twitter, in helping consumers find loopholes to save money.
Tesco launched a "double the difference" price guarantee earlier this year in a bid to prove it was cheaper than Asda, after the Leeds-based rival said it was 10 per cent cheaper than everyone else. Tesco responded by promising shoppers that it if they found exactly the same item at a rival supermarket it would pay out twice the difference, in the form of vouchers.
Soon websites, particularly the MoneySavingExpert.com forums, were full of consumers informing fellow shoppers about which items were cheaper in which store, spreading the news via Facebook and Twitter.
One customer, shopping for MoneySavingExpert.com, found that some alcohol, laundry products and pet food were cheaper at Asda.
He spent £126 at Tesco on a shop that would have cost £81 at Asda, and claimed a £90 voucher.