The RSPCA is considering whether to prosecute after an undercover investigation revealed horrific cruelty and abuse behind the scenes as sheep were sheared on British farms.

Animals could be seen writhing in agony as they were violently hit, punched and stamped on, and had their limbs twisted.

People for the Ethical Treatment of Animals, which carried out the secret filming, appealed for shoppers to avoid buying items made of wool, claiming the scenes were commonplace in the industry.

A Peta investigator reported seeing illegal cruelty in every one of the 25 English farming sheds visited by two shearing contractor companies over 15 days.

In the first secret footage ever taken of shearing in Britain, the witness saw panicked sheep being:

punched

beaten

stamped on

cut with shearing equipment

sewn up roughly with needles but no pain relief

held down with booted feet

slammed into a wooden floor by the head

thrown off lorries to the ground

left without veterinary care when painfully lame

killed and the carcasses thrown away

Donald Broom, professor of veterinary medicine at Cambridge University, said that sewing up a cut with no anaesthesia and throwing sheep – as the witness reported – caused pain and suffering to a degree that breached guidelines for legal practice by the World Organisation for Animal Health and other international bodies.

Such cruelty is illegal in most countries.

The footage shows how shearers stood on sheeps’ heads and necks, pinning them down to stop them moving, threw animals on and off the back of lorries, twisted their necks and limbs, and hit their heads and bodies on hard floors.

In other cases workers kicked animals in the stomach, violently punched them in the face and jabbed them in the head with heavy metal clippers. Some of the clips were too horrific for The Independent to show.

After rough shearing caused bleeding open wounds, shearers used needles – which the witness said did not appear to have been sterilised – to sew them up, without anaesthetic.

Australia’s multi-billion-dollar wool industry has been criticised in the past after Peta Asia previously revealed similar shocking practices. Six shearers there were charged with animal cruelty.

Clive Phillips, Professor of Animal Welfare at the University of Queensland, said: “Throwing sheep from a significant height … when they are in a state of extreme distress is likely to result in injury to the sheep, such as broken limbs or neck. [These actions were] deliberately inflicted and lasted for more than just a short period of time.”

The UK has more than 40,000 wool-producing farms, with 15 million sheep between them, according to industry body British Wool, which sells wool for farmers.

Most farms employ special contractors for shearing, whose employees are paid for each sheep shorn – creating an incentive to work quickly.

If an animal struggles, this slows work down and a flock will take longer to complete. CCTV is not compulsory for shearing.

A worker stomping on an animal's neck at a farm in England (Peta Asia)

The investigator said a shearer earned on average £200 a day if there are a lot of sheep, and an even faster shearer could earn more.

When the investigator visited, workers were filmed angrily swearing, saying “Bas****”, “Cut your f****** throat” and “What the f*** is wrong with ya?” as they used metal tools to beat or hold the animals down.

A farmer was reportedly seen dragging two sheep who were unable to walk into a shed and left them without veterinary care. They eventually died. Several more died during shearing of a condition that a farmer said was a “heart attack”.

Peta said some animals were suffering from mastitis – a painful infection of the udder – prolapsed uteruses and bloody hooves.

The whole wool industry needs to be held to account Andrew Butler

The shearers, who also work for other contractors around the UK, were filmed handling sheep as though they were inanimate objects, scraping their bodies and heads against the lorry edges as they dragged the animals on and off lorries.

Andrew Butler of Peta Asia said: “The whole wool industry needs to be held to account. Workers are paid piecemeal – to shear as many sheep as they can as quickly as they can and that of course results in the sort of injuries that we’ve seen. The industry is really at fault for using that model.”

The animal-rights group has handed its findings to the environment department (Defra) as well as the RSPCA, asking the charity to file criminal charges against the workers.

In a statement, British Wool told The Independent it was “shocked and saddened” by the behaviour of the two contractors filmed secretly.

“As a farmer-owned organisation, British Wool collects and sells the wool on behalf of British farmers. We are passionate and committed to continuously seeking to improve shearing skills and good practice in the UK,” a spokesperson said.

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“Every year we train more than 1,000 people in all parts of the UK on two-day training courses that are tailored to their existing level of experience and skill.

“It is not within our remit to police the shearing industry: this responsibility lies with the government and the RSPCA.”

The RSPCA will be making a full investigation into the footage, the statement said, adding: “We will provide them with any support required.

“We would like to point out that the vast majority of the thousands of shearers in the UK operate to the highest standards of animal welfare, which is an integral part of all our shearing courses.”

The RSPCA, which has prosecution powers, said on Twitter: “We share Peta’s concerns in particular of the poor handling, shearing technique and aggression shown toward the sheep. Our Inspectorate are now investigating the footage to determine any further action.”