Tesco has cut back its offer to refund double the difference on products bought for less in Asda, blaming "savvy" shoppers.
The supermarket giant said that it would now only refund the difference in price - rather than double the difference.
It claimed that a "cottage industry of savvy and determined people" had been making money from the promotion.
In March, Tesco introduced a £20 maximum refund.
The supermarket said that some people were identifying products on promotion at Asda, then buying the same products at Tesco.
They would then get double-the-difference coupons and buy more of the same products with the coupons.
"Some people have misused the scheme to cash in," a Tesco spokesman said.
An Asda spokesman said: "Clearly they found it hard to make a promise they could not keep."