Tesco has vowed to explore eradicating sow stalls from its Thai supply chain after animal welfare campaigners accused the supermarket chain of selling pork products from farms where mother pigs are kept in steel cages “no bigger than a fridge”.

Also referred to a “pregnancy cages”, sow stalls have been banned in the UK since 1999, but World Animal Protection accused Tesco Lotus, Tesco Group's second largest business outside the UK, of selling pork products from animals kept in them.

About 40 per cent of pigs are kept outside in the UK where they can roam free and perform more natural behaviours when giving birth, while the rest are kept indoors in group housing, World Animal Protection said.

“Why should a mother pig have to suffer under the Tesco brand just because she’s been born and raised in Thailand." said Ian Woodhurst, the organisation's farming campaigns manager. “She would normally roam around foraging for food, socialise with other pigs and build a nest for their piglets.

“On a factory farm she cannot do any of this, trapped in a tiny steel cage where she can barely move. Supermarkets have the power to make a change for farm animals.

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“We’re urging Tesco to stop this misery and improve the lives of mother pigs on farms that supply its 2,000 Tesco Lotus stores across Thailand.”

The organisation also called on Tesco to introduce a global pig welfare policy “to stop this barbaric practice on farms that supply its stores worldwide”.

It has already had succeeded in persuading CP Foods, a Thai pork producer, to get sows out of cages in their operations by 2025.

Tesco said no Thai pork is sold in the UK – however it said it was working with its suppliers in the region to “explore” how it could move sows “out of stalls and into group housing”.

World Animal Protection has called on Tesco to eradicate sow stalls from its Tesco Lotus supply chain in Thailand. (World Animal Protection)

Tesco Lotus is Tesco Group’s second largest business outside the UK. It operates a network of more than 2,000 stores across Thailand.

“We take care to uphold high standards for animal welfare right across our supply chains which we continuously review according to the latest scientific advice," a spokesman said. "All the pork meat sourced by our Thai business is certified by the Thai government which sets the standards for animal welfare in that country.