WestBusiness reports that the activists allegedly tracked the pigs shown in the footage to Coles' stores but the claims were discredited after an investigation instigated by the supermarket found the video evidence had been heavily edited and included images not taken at the WA piggery.

According to Coles, it is not uncommon for animal welfare groups to come to the company with allegations against farmers who are always fully investigated.

"We support the objectives of animal welfare groups to uphold animal welfare standards but do not condone any unlawful practices in the gathering of material," Coles said in a statement to WestBusiness.

It is unclear when the footage was taken but the WA Pork Producers Association said industry members had contacted police about the break-in. Pork producers throughout Australia have been the target of break-ins in recent months, with peak body Australian Pork Limited reporting four cases, including two at piggeries near Young in NSW.

The Craig Mostyn Group, which owns and operates WA's biggest processor Linley Valley Pork, said the industry worked closely with the RSPCA and retailers such as Coles on animal welfare issues, but was alarmed about the actions of extremists who broke the law and fabricated evidence of cruelty.

CMG chief executive David Lock said the break-in had not occurred at one of Linley Valley's five farms but Coles had alerted the company to the allegations. "The allegations were very distorted. Coles took it seriously but once they looked at the facts it was clear what was being alleged was impossible," Mr Lock said.

Mr Lock said extreme activists deliberately distorted conditions on farms and ignored the millions of dollars invested by industry to improve animal welfare standards, including the phasing out of sow stalls. "They break in at night, upsetting the animals so there is a lot of squealing and noise, and then produce grainy pictures in a deliberate misrepresentation of farm conditions," he said.

"There is also a risk to staff if they encounter intruders at night. We also have very high biosecurity standards to ensure diseases don't come on to our farms. Break-ins don't put one farm at risk but a whole industry."

WA produced 37,100 tonnes of pork in 2011-12 with about 20 per cent exported to South-East Asia.

The footage from the WA break-in appeared on the Animal Amnesty website before being taken down. Animal Amnesty did not respond to a request for comment.

The WA-based group has said previously that it is an outlet for film and other material submitted by the public but does not condone illegal activity.