Footage has been captured by animal rights group The Animal Justice Project of RSPCA-approved workers apparently stamping on hens at a farm that supplies eggs to the Co-Op and Morrisons.
The secret footage was captured by an investigator working for the animal rights organisation, while undercover at Kettleby Farm in Leicestershire.
It shows the work of a 'catcher' gang from AD Harvey, who was hired by the farm to carry out a depopulation process whereby the chickens are rounded up and taken to an abattoir when they reach the end of their natural egg-laying life.
Morrisons has confirmed the farm was a supplier to its supermarkets, while the Co-Op has not yet commented.
AD Harvey and Kettleby Farm, which is owned by Sunrise Poultry, are both RSPCA Assured members. However, RSPCA Assured has since suspended AD Harvey whilst they investigate the alleged abuse.
In the footage, a group of workers from the company can be seen stamping on and kicking the animals and later carrying at least nine chickens in one hand before loading them into crates.
Catcher gangs are used at chicken farms across the UK to catch thousands of chickens when they come to the end of their natural egg-laying life.
The Animal Justice Project claims that in one incident, around 30,000 hens at the end of their egg-laying life were caught in one night at the Kettleby Farm.
They also say that similar incidents have been reported at farms in Kent, Oxfordshire, and Bedfordshire.
AD Harvey says that staff in the footage are no longer employed and their remaining staff are undergoing retraining.
Veterinary Professor of Animal Welfare, Andrew Knight, said: "Workers engaged in incorrect and injurious handling techniques, including kicking and hitting hens, treading on them, and violently throwing them against shed walls.
"Some hens were severely injured or dead, while others experienced extreme distress, being carried upside down or by one leg. Additionally, workers were observed slamming doors onto hens, causing potential harm.
"These actions are not in line with humane or ethical treatment of these highly sentient birds and likely violate UK animal welfare legislation."
Animal Justice Project is now calling on the RSPCA to cut all ties with AD Harvey.
Spokesperson for Animal Justice Project, Claire Palmer, said: "Today, we expose some of the most appalling acts ever captured on film.
"Faced with indisputable violence against hens, the RSPCA must take decisive action beginning with the permanent severing of ties with AD Harvey and the launch of criminal proceedings against potential law violators.
"The distressing, breakneck speed at which hens, at the close of their productive lives, are nightly captured by gangs under the watch even of the RSPCA underscores the urgency for a shift away from animal agriculture.
"It's a compelling call for a transition to plant-based farming, prioritising compassion over cruelty in our food production systems."
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