Image caption The government plans to hold a public consultation on animal welfare later this year

The government is facing renewed calls to curb the slaughtering of animals that have not first been rendered unconscious - a debate that pits religious sensitivities against the convictions of animal welfare campaigners.

Senior Conservative backbencher Greg Knight has told MPs that the practice of slaughtering cattle, lambs and chickens in this way is "rife".

The law demands that animals be stunned before they are killed - by electrocution, gassing, or shooting retractable rods into their brains - but there are exemptions for animals to be killed according to Jewish and Muslim traditions, without stunning them first.

In the Commons on Thursday, Mr Knight described these exemptions as "unacceptable".

This is the culmination of a series of interventions from the Conservative backbenches in recent weeks, adopting progressively more hardline stances on the subject.

The previous week, Conservative MP for Ealing Central and Acton Angie Bray claimed that "more than 25% of meat sold in our shops comes from animals that have not been stunned before slaughter".

'Freedom of choice'

As this amount "exceeds easily the needs of our communities with special religious requirements", she suggested that some abattoirs were using the exemptions for kosher and halal meat as an excuse to cut costs.

"New measures" might be needed to enforce the law properly, she said.

Religious slaughter Jewish method called shechita

Stunning prohibited in Jewish law, which says animals must be healthy and uninjured at the time of slaughter

Muslim method called dhabiha

Islamic law also says animals must be uninjured, but some authorities allow a form of stunning (in the UK, dhabiha usually involves stunning) Viewpoints: The right way to slaughter?

And last month, Tory MP for Shipley Philip Davies launched a bid to change the law to ensure that halal and kosher meat on sale in shops and eateries was labelled as such.

"My sole reason for introducing the bill is to give consumers more information, so that they can exercise their freedom of choice," the former Asda employee told MPs.

Mr Davies said his objective was to ensure that consumers knew "how the meat has been killed".

Kosher meat is not processed in the UK from animals stunned prior to slaughter.

But EU research from 2006 indicated that 75% of cattle, 93% of sheep and 100% of chickens slaughtered in the UK for halal meat were stunned prior to their deaths. Figures produced by the Food Standards Agency (FSA) in 2011 give a similar picture: 84%, 81% and 88%, respectively.

Meanwhile, Denmark and New Zealand have both legislated to ensure that all animals killed for halal meat are stunned first.

So labelling meat as halal will not fully achieve Mr Davies' objective, since consumers will be unaware whether the animal had been stunned or not.

Commons canteen

MPs were quick to point out flaws in Mr Davies's bill, before voting to consign it to the legislative scrap heap by a majority of just three.

"If it said that all chickens had to be labelled in a certain way if the birds had been battery hens, or if he had proposed that meat had to be labelled in a certain way if the animals had been kept in dreadful conditions before being killed... I would at least regard him as consistent," Sir Gerald Kaufman said.

The veteran Labour MP accepted that Mr Davies had not the "tiniest anti-Semitic feeling in him", yet he had come forward with a bill that "picked on two small minorities".

Concerns about the extent to which non-Muslim consumers are unwittingly eating halal meat were voiced during the recent French presidential campaign by far-right candidate Marine Le Pen, before being taken up by Nicolas Sarkozy, who declared that it was the "issue that most preoccupies the French" as he failed in his bid for re-election.

These concerns were echoed in the Commons by Mr Davies, who told MPs that "state schools, hospitals, pubs, sports arenas, cafes, markets and hotels [are] serving halal meat to customers without their knowledge".

Reports have also revealed that halal meat has been served in the House of Commons canteens without labelling.

'Stricter rules'

While committing itself to the principle of providing accurate information to consumers, the government has warned that there are "real practical difficulties in establishing traceability to identity method of slaughter to the point of consumption".

Finding out exactly how much halal and kosher meat is being sold in the UK is also problematic, since accurate data on the subject is not gathered.

Ms Bray's 25% figure for halal meat appears to be based on a recent article by former president of the British Veterinary Association, Bill Reilly - but he emphasises that some of these animals would have been stunned before slaughter.

The FSA estimates that less than 1% of all meat produced in the UK is kosher.

Members of the lower house of parliament in the Netherlands agree with Mr Knight's suggestion that slaughter without stunning is "unacceptable".

The chamber recently voted in favour of an outright ban, but the legislation was subsequently blocked by the senate after the country's Chief Rabbi, Binyomin Jacobs, reportedly drew a parallel with Nazism.

"One of the first measures taken during the occupation was the closing of kosher abattoirs," he said.

Although no changes to the current regime on religious slaughter are mooted in a new EU directive on animal welfare, due to come into force in January 2013, Environment, Food and Rural Affairs Minister James Paice has noted that "member states can impose stricter rules in relation to religious slaughter if they wish".

He added: "I am currently considering what might be done to improve welfare in this context."

The UK government plans to consult on how to bring the directive into force later this year, giving an opportunity for both proponents and opponents of the current regime to rekindle the debate.