The UK's Advertising Standards Authority (ASA) has banned two Waitrose ads after it ruled claims about pigs' living conditions were misleading.

The ads, which featured celebrity chefs Heston Blumenthal and Delia Smith, said the pigs were "outdoor bred" despite them being reared indoors after weaning.

In the first ad, Blumenthal said: "In my opinion, some of the best tasting pork comes from British pigs that have been outdoor bred, just like these porkers from Norfolk. And this is where it all begins. Phil Ellis has been supplying quality British pork for the past 18 years. So, Phil, what is it about outdoor bred pigs that makes the meat taste so good?"

The farmer then replied: "I think it's got to be the environment they're living in; plenty of fresh air, cereal-based diet and of course a comfortable bed."

The ASA received five complaints from members of the public, who challenged whether the ads misleadingly implied that Waitrose's pork came from pigs that spent the duration of their lives outdoors, whereas they understood the pigs were reared indoors in confined conditions after a few weeks.

Waitrose countered the claims by saying that "outdoor bred" was a standard term in the pig farming industry, with pigs born in fields, where they were kept until weaning, and then they were moved indoors, into light and airy sheds with straw.

However, the ASA banned the two ads because while the term "outdoor bred" might be commonly understood in the pig farming industry, it ruled that the average consumer was unlikely to be aware of its particular meaning. "Without any explanation of its meaning, we considered readers were likely to understand 'outdoor bred' to mean that the pigs used to produce the product spent the duration of their lives outdoors," the ASA said.