Spy-cam footage from a halal slaughterhouse where sheep have their throats cut without being stunned has led to action by the Food Standards Agency (FSA).
Four slaughtermen at Bowood Lamb abattoir in Thirsk, North Yorkshire, have had their operating licences suspended and an investigation is under way.
Prosecutions may be considered in light of the alleged "horrifying yet routineabuse" captured on film by the animal rights group Animal Aid.
Hidden cameras were smuggled into the abattoir and left recording over a period of three days in December.
Kate Fowler, head of campaigns at Animal Aid, told ITV News it was common across the country:
The law requires abattoirs to stun animals before slaughter to preventunnecessary suffering, but there are exemptions for Jewish and Muslimproducers.
Under UK law, slaughtered animals that have not been stunned must remain in position for at least 20 seconds after their throats are cut, to ensure loss of consciousness.
But 86% of the sheep at Bowood were moved before that amount of time had elapsed, some in as little as one second, according to Animal Aid. They said the average bleed out time allowed for the animals was just under 13 seconds.
Although Government-appointed vets are supposed to be on hand in all abattoirs the size of Bowood, none were seen during the three days of filming.
Animal Aid stressed that when it gained access to the abattoir - by legal means - it did not know it was a non-stun establishment.
Equally shocking welfare breaches had been uncovered at other secretly-filmed slaughterhouses where animals were stunned.
Animal Aid is calling for independently monitored CCTV cameras to be compulsory at slaughterhouses.
A petition aimed at triggering a parliamentary debate on the issue has already collected more than 80,000 of the 100,000 signatures needed.
It has received the backing of celebrities including comedian Ricky Gervais,actress Sadie Frost, and Queen guitarist Brian May.
Animal Aid said it recognised there was a risk of the video stirring upanti-Muslim feeling, but added: "Witholding release of the footage would be a betrayal of our key mission: to expose and combat animal cruelty."
Figures released by the British Veterinary Association last week show that thenumber of animals undergoing ritual slaughter without stunning has soared in the UK in the past year.
Campaigning by Muslims for traditional methods of slaughter is said to have led to a 60% rise in the number of animals having their throats cut whileconscious.
Last year, 2.4 million sheep and goats were killed without being stunned inhalal and Jewish shechita abattoirs, according to the BVA.
Slaughterhouses in the UK are regulated by the FSA, which provides operating licenses and carries out inspections.
Asked about the allegations, William Woodward, one of the abattoir's directors, said: "We have no comment to make."