Disturbing footage showing "routine abuse" of sheep in a halal slaughterhouse has reignited the debate over whether animals should be stunned before they are killed for meat.

Under halal law, animals are supposed to be killed quickly by single cut from a surgically-sharp knife .

Although 80 per cent of halal meat is stunned, the number of sheep killed without stunning is rising due to campaigning by Muslims, figures show.

Secret filming in an halal abattoir in Yorkshire showed "horrifying" treatment of animals killed without stunning.

An operative in Bowood slaughterhouse in Thirsk grabs a sheep by the neck

Workers were shown hacking and sawing at the animals' throats with apparently blunt knives. In one instance the procedure, which according to Islamic law should be instantaneous, took five attempts.

Halal rules also state that animals should never see the knife or witness others being killed, protecting them against unnecessary trauma.

But the footage showed a man wearing a Muslim kufi skullcap at Bowood Lamb abattoir in Thirsk regularly sharpening knives in front of the sheep. Due to the design of the slaughterhouse, in which animals were forced on to conveyor belts, the sheep typically saw another member of the flock having its throat cut, bleeding on the floor and being hoisted and shackled.

In a direct contravention of animal UK animal welfare law, 431 of the 500 sheep observed were "shunted off" the conveyor within 20 seconds of being cut.



A slaughterman teases one of the sheep as it is pushed on to a conveyor belt

British law prohibits the slaughtering of animals unless they have been stunned, but there are exemptions for Jewish and Muslim producers.

Religious leaders from both communities have always insisted that halal and and kosher meat is produced in a humane way.

The film captured by lobby group Animal Aid, which has used subterfuge to place cameras in 10 abattoirs since 2009, showed evidence of repeated malpractice.

John Blackwell, president of the British Veterinary Association, said: "Slaughter without stunning unnecessarily compromises animal welfare at the time of death and as such we call for an end to its practice.

"The Animal Aid film is truly shocking. Whether in a stun or non-stun abattoir these abuses would warrant sanctions under the current welfare legislation."

The group has collected more than 100,000 signatures for a petition to have the issue of stunning animals debated in Parliament. It has gained the backing of celebrities including Ricky Gervais, actress Sadie Frost and Queen guitarist Brian May.

Awal Fuseini, of the Halal Food Authority, condemned the practices in the video as unrepresentative of halal slaughtering and against Islamic law.

"Any imam [Islamic leader] who looks at this video would be disturbed," he said.

"Every activity is a contravention of animal welfare standards – the operatives are poorly behaved and trained, the knives are not sterilised and do not appear sharp.

"These are very special circumstances and have nothing to do with stunning or non-stunning."



Workers laugh and joke as the sheep is transported for slaughter

The number of sheep and goats killed without stunning rose 60 per cent to 2.4 million last year, according to the Food Standards Agency.

On receiving the video evidence, the regulator immediately suspended the licence of the slaughtermen involved and initiated an investigation.

"There is no excuse for treating animals in the way shown on the video and we are therefore investigating the footage with a view to prosecution," a spokesman said.



Slaughtermen 'hacked away' at the animals' necks with blunt knives

Kate Fowler, head of campaigns at Animal Aid, said the footage was among the "most extreme" examples of animal abuse in the 10 films captured. It was the first video showing meat killed in a religious manner.

Workers at Bowood stamped on sheep, kicked them in the head and shouted at them as they attempted to transport them to onto the conveyor belt. Ms Fowler said the poor design of the slaughterhouse made matters worse.

However, she said such treatment was unrelated to religious practice and called for CCTV to be placed in every abattoir.

Earlier films at slaughterhouses that did use stunning had shown animals being punched in the head, burnt with cigarettes, beaten with sticks, given electric shocks with stunning tongs, thrown and kicked.

A spokesman for Bowood abattoir was unavailable for comment.