Britain's dairy industry suffered a blow after the advertising regulator said a vegan campaigning group is allowed to describe milk production as inhumane.

The Advertising Standards Authority (ASA) made the ruling on an advertisement placed in newspapers by the campaign group Go Vegan World which stated "humane milk is a myth".

The group says that drinking milk is cruel to cattle which it claims are bred to maximise production.

The advert claimed calves "cried piteously" when they were separated from their mothers when "fresh from their wombs".

The advertisement sparked complaints including from the National Farmers' Union, which will appeal the ASA decision.

NFU chairman Michael Oakes told the Times that the vegan advert was misleading and "our members, who are constantly looking to improve welfare standards, found it upsetting and demoralising".

But the ASA ruling stated that while the language used was "emotional", the fact that calves are separated from their mothers soon after birth meant that "the ad was unlikely to materially mislead readers".

David Bowles, from the RSPCA, said it was incorrect for the advert to claim all dairy farming was inhumane, telling the paper: "You can rear, transport and slaughter an animal according to good welfare standards and therefore they can be humanely . . . eaten."

Sandra Higgins, director of Go Vegan World which is based in Ireland, has said the dairy industry has been trying to silence her group.

"We have been having this debate for hundreds of years on how to improve the conditions of those animals we use and it hasn't been effective. We wouldn't swap places with them," she said, according to the Times.

The Telegraph, which originally ran the advertisement back in February 2017, reported that Higgins, from Slane in County Meath, initially campaigned in Ireland, but expanded her advertising campaign to other countries, last year focusing on Birmingham, Wolverhampton and Newcastle Upon Tyne.

The ruling comes only a couple of months after dairy farmers lost an ASA case after the regulator ruled that advertising organic milk as "good for the land" was misleading.