Tesco has stuttered in its price war with Asda since the New Year, against a background of increasing pressure on consumer spending.
Asda took the initiative in January, pledging to pay customers back the difference in price plus 10% if rival supermarkets were found to be cheaper.
Tesco signalled the start of a climbdown earlier this month, capping refunds at £20 as websites had advertised where consumers could cash in on price differences.
Now it will give just the difference in price, blaming consumers for over-exploiting the deal.
Tesco, in a statement issued this morning, said: "Price Check has given our customers confidence in our prices and transparency. But some people have misused the scheme to cash in. So we have taken this step to protect Price Check for the majority of our customers."
An Asda spokesperson said: "Clearly they [Tesco] found it hard to make a promise they couldn't keep."