The UK's Advertising Standards Authority has found that Asda's marketing campaign comparing its prices with those at Morrisons was "misleading".

The advertising watchdog considered a six-point complaint by rival Morrisons over two ads that appeared in the national press earlier this year.

The two adverts compared baskets of shopping from the rival supermarkets. The first contained 44 products at a cost of GBP69.33 in Asda and GBP76.65 in Morrisons. The second contained 48 products and cost GBP65.68 in Asda and GBP76.65 in Morrisons.

The ASA found that the ads used time sensitive promotional items at Asda and didn't take into account offers at Morrisons. Indeed, the price of one product included - a bottled beer offered by Asda at a discounted price - increased before the commercials finished airing.

Additionally, the ASA was critical that the commercials didn't identify the products used for comparison.

"When we investigated the complaint put forward by Morrisons we found the ads breached the advertising code," a spokesperson for the ASA told just-food.

This is the second warning Asda has received for failing to make clear when promotional prices were being compared with regular prices, the ASA said.

Asda was told that it could not repeat the ads and warned to consult CAP Copy Advice before publishing comparison ads in the future.

Asda could not be reached for comment as just-food went to press.