Warning: The video below contains images some viewers may find distressing
Supermarket giant Morrisons says it is investigating an undercover video which appears to show pigs being beaten and pushed with paddles at one of its abattoirs.
Staff were secretly filmed by activists from the Animal Justice Project using electric prods and paddles on animals arriving at the Woodhead Brothers slaughterhouse at Pinchbeck, near Spalding, Lincolnshire.
In one section of the video an injured pig appears to be kicked as it struggles to walk.
The animal rights organisation said its investigation has revealed "a brutal culture towards animals" which violates animal welfare laws.
Claire Palmer, from the Animal Justice Project, said: "We were expecting footage that wouldn't be very nice to see... but it was actually worse than we were expecting. We weren't expecting to see such excessive, brutal hitting of pigs."
Amelia Beckett reports from Pinchbeck, Lincolnshire
Andrew Knight, a professor of animal welfare, said the video appeared to show breaches of rules on the treatment of animals.
He said: "The Defra code of practice... specifies that pigs should not be rushed, they should be allowed to move at their own pace. Pigs certainly shouldn't be hit repeatedly, they shouldn't be hit on the head, they shouldn't be panicked."
Morrisons claims it is the only major supermarket chain to own its abattoir and meat processing operations, which it says gives it unique control of the supply chain.
The company said its CCTV was independently reviewed as "a clear way to demonstrate that we have the highest possible standards".
However, Animal Justice Project said CCTV was "failing to prevent poor practice".
The organisation said when animals were being transported, "care was not taken to ensure they were not frightened, excited or mistreated".
A spokesperson for Morrisons said: "We care deeply about animal welfare, both in our own operations and throughout our supply chain, and we're confident that our training and monitoring systems are among the best in the industry.
"There is however very concerning footage of a pig that arrived at the abattoir with a clear injury to its front leg. We are looking carefully into how this happened.
"The video also shows more forceful than necessary use of the rattle - which is totally unacceptable - and will be dealt with."
The company added that they would be increasing training of third party hauliers and Morrisons colleagues.
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know.