The TV and print ads, which broke in October 2014, sparked a complaint from rival Aldi, which took issue with Morrisons' price matching system against Tesco, Sainsbury’s, Asda, Lidl and Aldi.
The spot shows Ant visiting a variety of supermarkets to find the cheapest options, while Dec relaxes outside a Morrisons branch with his shopping.
The adverts state that any price difference calculated at a Morrisons checkout would be added to the shopper’s Match & More card.
But Aldi complained to the Advertising Standards Authority that the ads were misleading and that Morrisons failed to verify for customers how they had compared their prices against the other supermarkets, and how they had calculated the points total. There were 18 complaints in total surrounding five issues, all of which were put forward by Aldi.
The ASA investigated the claims and ruled that the ads were not misleading, but upheld one of the complaints because: "We did not consider Morrisons had provided a clearly signposted facility for customers who had shopped with them to obtain readily, specific details of what products had been compared, and at what prices, to explain how the points total had been calculated."
For this reason, the ASA ruled that Morrisons was "not to repeat the ads until they had ensured that they provided consumers (and competitors) with a sufficient method to verify the references to the price-match scheme."
Tony Baines, a joint managing director of buying at Aldi, said: "We are pleased with the ASA's decision to instruct Morrisons not to run the Match & More adverts again in their current form.
"This supports our view that these adverts did not provide consumers with sufficient price comparison data to enable them to make an informed choice.
Since the ruling, Morrisons has rectified their online content with a clearer methodology for accessing price comparison information, so the ad can continue to run.
Ian Twinn, the director of public affairs at ISBA, said there were already rules in place to ensure price comparison data was properly referenced by advertisers and said he was "relaxed" about consumers' ability to trust the claims made in such ads.
He said: "The rules on price comparison are quite strict. But clearly there is an issue when this complaint was made in October and here we are nine months later talking about it, well after the time when prices would have changed. There is no retrospective action that can be done but it is a warning to all supermarkets to be accurate."
Commenting on the initial halt to the ads, Martyn Jones, the Morrisons Group corporate services director, said: "This was a reasonable request which we quickly resolved. Shoppers with a receipt have always been able to discuss their savings with our customer services team but we have also made information clearer on our website. Overall the ASA’s ruling is a convincing outcome."