The advertisement that appeared in the national press on posters and in magazines was promoting the Quality Pork Standard Mark.

The poster was headed "Pork: A Guide to the Cuts" and featured an illustration of a pig in the style of a butcher's diagram showing different cuts of pork.

Instead of naming the cuts of meat the diagram was labelled "1.Cut in Income 2.Cut in Jobs 3.Cut in Farms 4.Cut in Quality 5.Cut in Consumer Choice.

More text around the diagram said: "British pig farms have very high welfare standards, assured by the Quality Standard Mark. And well cared-for animals mean better quality meat ... Help the pig farmers. Sign our petition for fairer prices at pigsareworthit.com and always look for the Pork Quality Standard Mark."

The press ads were headlined: "Save a rare British breed from extinction. No, we don't mean the pig."

And the text read: "When British pig farmers aren't up to their knees in whatnot, they're increasingly likely to be up to their necks in debt ... Many face financial ruin and are sadly giving up on pigs altogether. So what caused this crisis? Well, pig farmers in the UK already face higher costs than those in Europe, largely due to our higher standards of pig welfare. But the global rise in wheat prices has driven up the cost of feeding pigs worldwide ... "

Compassion in World Farming and one member of the public challenged whether the claim "British pig farms have very high welfare standards" in the poster campaign was misleading and could be substantiated.

Vegetarians International Voice for Animals (Viva!) challenged whether the claim "pig farmers in the UK already face higher costs than those in Europe, largely due to our higher standards of pig welfare" in the press and magazine ads misleadingly exaggerated the standards of pig welfare on UK farms.

BPEX told the Advertising Standards Authority that they did not accept that the statement "British pig farms have very high welfare standards" meant that the standard of pig welfare was very high.

They said it was their fundamental belief that the statement related only to the welfare criteria that were controlled by Quality Standard Mark (QSM) standards.

They said they did not see very high welfare per se in pigs as a natural interpretation of the statement.

They emphasised that the standards of welfare required by the QSM were in themselves significantly in advance of those required by and generally practised in the rest of the European Union (EU) and went beyond the "Defra Code of Recommendation for the Welfare of Livestock - Pigs".

However, the Advertising Standards Authority upheld the complaint from Compassion in World Farming and the member of the public.

The ASA said: "The ASA considered the evidence sent by the British Pig Executive. We noted their assertion that the claim "British pig farms have very high welfare standards, assured by the Quality Standard Mark" did not imply the welfare of pigs was in itself very high, but would be understood by readers to mean that the welfare standards were themselves very high.

"However, because the claim was followed by the text "And well cared-for animals mean better quality meat", we considered it did imply the welfare of the pigs was very high, and not simply that the standards themselves were very high."

The ASA acknowledged that the QSM represented higher standards of welfare than in some European countries, particularly over the issues of castration and the use of stalls and tethers, but it said that there was no indication about how welfare in Europe should be measured.

In a statement following the decision BPEX said that it "will continue to maintain that the QSM continues to reflect very high welfare standards particularly when compared to the rest of the EU. The banning of sow stalls by UK Government legislation since 1999, which is still widely practiced on the Continent and the continued use of castration, which is prohibited within the QSM, lie at the core of this claim. Until such time as there is a level playing field on welfare standards across the EU, BPEX will continue to promote its QSM on the basis of very high quality welfare."

BPEX Head of Marketing Chris Lamb said: "We lost on a technicality because we did not connect the claim made directly with a comparison to the rest of Europe, particularly with reference to sow stalls and castration. We shall obviously make sure we do in the future."

BPEX Chairman Stewart Houston said: "Welfare is an important area for the British pig industry and BPEX will continue to maintain its standards whilst at the same time engaging in constructive debate to raise standards still further."

The complaint by the vegetarian group VIVA was thrown out by the ASA.