An Aldi advert challenging viewers to "swap and save" on their regular supermarket has been banned after rival Asda complained that it would mislead consumers.
The television ad featured a woman, who had taken up the challenge and shopped at her usual supermarket for four weeks and then at Aldi for four weeks, saying: "...it's cheap and it's good.
"I think £45 a week is a lot of money given that we've got to spread it so thinly amongst so many things. So it's definitely worth doing for us. Meaning that we can go on an extra holiday a year."
Text at the bottom of the screen said 88 out of 100 people saved money between April 1 and May 26 last year.
But Asda said the ad was misleading because the selected elements of the comparison could give Aldi an unrepresentative advantage, the basis of the comparison and savings claims was unclear, the type of products could not be verified and the time of the comparison was out of date and invalid for a price sensitive market.
Asda also complained that the "extra holiday" claim implied that savings achieved in one month would produce similar savings in the future, when this could not be substantiated on the basis of the swap and save comparison.
Aldi said Asda had mistakenly interpreted the campaign as a price comparison, but pointed out that the ad asked if consumers could "swap and save" rather than making a specific claim.
Aldi said the £45 figure had clearly not been arrived at by individual product price comparisons, and the basis of the comparison of cost was by reference to the woman's overall weekly spend at the two stores.
The Advertising Standards Authority (ASA) noted that swap and save participants had been told to conduct their weekly shop as usual, but said a number of items were excluded from the total savings which could have given Aldi an unrepresentative advantage.
It also noted that the data was several months old by the time the ad aired.
The ASA ruled that the ad must not appear again in its current form, saying: "We told Aldi to ensure that the basis for comparisons were made clear in their future ads and that they should be able to provide substantiation for any savings claims made on the basis of these comparisons.
"We also told them that, in order to make the comparison verifiable, they should amend the ad to include either a postal address to which viewers could write for full details of the comparison, including which products were included and at what prices, or a web address that linked directly to a page about the campaign that included such details or a postal address."