Belgian animal welfare organisation, Gaia, is calling on men to go without underpants this Friday as a protest against the castration of pigs.

But the UK's National Pig Association chairman, Stewart Houston, has told British men to keep their pants on.

He said: "As is often the case in matters of animal welfare, the UK is already ahead of the rest of Europe.

"Although castration is not actually banned in the UK, it is not allowed under our farm assurance schemes which account for 92 per cent of the pigs in the UK. That's why consumers who want high animal welfare standards should look out for the Red Tractor mark on their pork products."

The Gaia campaign is called 'let them dangle' and is intended as a 'gesture of solidarity for the five million piglets needlessly castrated without anaesthetic every year'.

Girlfriends and wives are invited to show their support for the campaign by hiding their partners' underwear. Gaia hopes that the strength of feeling resulting from the protest will encourage supermarkets and farmers to turn their backs on the practice of piglet castration in Europe.