One hundred MPs have signed a parliamentary motion calling for CCTV cameras at all UK slaughterhouses.
Jim Cunningham, Labour MP for Coventry South, became the 100th MP to sign the early-day motion tabled by Grahame Morris, Labour MP for Easington.
The call for CCTV to be fitted in all slaughterhouses in the UK is supported by more than half of all members of the Welsh Assembly Government.
The campaign for mandatory CCTV with independent monitoring of the footage has attracted widespread support.
As well as the public showing their strong support via a YouGov poll and a Number 10 petition, it has the backing of Unison, the union representing meat hygiene inspectors and slaughterhouse vets.
Vets including Emma Milne, Pete Wedderburn and Marc Abraham and animal protection groups such as the RSPCA and Compassion in World Farming have also backed the campaign.
The 10 leading supermarkets, along with food service wholesaler Booker and Freedom Food (RSPCA), all insist that their slaughterhouse suppliers have CCTV cameras fitted.
But the footage is not yet monitored thoroughly by an independent body that could take robust action should welfare breaches be revealed.
Animal rights group Animal Aid called for mandatory CCTV in 2009 when it first placed fly-on-the-wall cameras inside UK slaughterhouses.
Over the past six years, its hidden cameras have revealed that nine of the 10 randomly chosen slaughterhouses were breaking animal welfare laws.
They recorded animals being kicked, slapped, stamped on, and picked up by fleeces, legs and ears and thrown into stunning pens, as well as animals being improperly stunned and coming round again, or suffering painful electrocution instead of being stunned.
In one non-stun slaughterhouse, the conscious animals’ throats were hacked at with a blunt knife. Elsewhere, animals were punched in the face, had shackle hooks embedded in their heads, and were mocked and tormented as they suffered abuse.
In March 2012, as a result of Animal Aid’s footage, two men were jailed for beating and burning pigs with cigarettes.
Animal Aid’s slaughter consultant Kate Fowler said: “Currently, taxpayers are charged millions of pounds every year for a welfare system that is failing animals.
“Clearly, things must change. We need a more robust system, and CCTV – if independently monitored – can play an important part in deterring and detecting welfare breaches.
“We are very grateful for the support of these compassionate MPs, who can see that action must be taken to hold the industry properly to account.”
However, a recent Farm Animal Welfare Committee report stopped short of recommending that CCTV should be mandatory in slaughterhouses.
According to Food Standards Agency estimates, in the UK 94% of cattle, 96% of pig, 90% of sheep and 99% of poultry throughput now comes from slaughterhouses with CCTV in use.
Defra said these figures suggested that it might not be necessary to legislate for change to happen.
A spokesman said: “The new regulations in England improve the protection of animals by maintaining our strict welfare rules in slaughterhouses while allowing for tougher enforcement action.”