Food safety records at the largest supplier of chicken to UK supermarkets have been tampered with - meaning consumers could have been duped into buying out of date chicken, according to an investigation by The Guardian and ITV.
Undercover footage obtained by the media outlets shows 'workers altering the slaughter date of poultry being processed at a 2 Sisters Food Group plant'.
According to the investigation: "The group produces a third of all poultry products eaten in the UK and supplies top grocers including Tesco, Sainsbury’s, Marks & Spencer, Aldi and Lidl.
"When informed of the evidence, all five retailers responded to say they would launch immediate investigations."
The undercover footage obtained by The Guardian and ITV was taken at 2 Sisters’ plant in West Bromwich over 12 working days. More than 20 workers were interviewed during this time as part of the investigation.
The footages shows: "Chicken portions returned by supermarket distribution centres are being repackaged by 2 Sisters and sent out again to major grocers.
"Workers drop chickens on the floor of the processing plant and return them to the production line.
"Chickens slaughtered on different dates are mixed on the production line. Workers said use-by dates printed on the packets of the mixed chicken tended to reflect the age of the freshest, rather than oldest, meat in the batch.
"Workers alter records of where chickens were slaughtered, potentially hindering authorities from recalling contaminated meat during food scares."
According to one worker: "I have [changed the slaughter dates] lots of times when I was working in that area.
"My supervisor, he asked me do it… If you are buying fresh chicken it can be older chicken."
Changing so-called 'kill dates' can give meat products an artificially longer 'commercial life', according to experts, as this can trigger 'the food processor to print incorrect use-by dates on supermarket packaging'.
Dr. Richard Hyde, an expert in food law at Nottingham University, said: "If you are placing a use-by date that is incorrect that is a breach of law. If you place food on the market that doesn’t have the correct traceability information that is a criminal offence."
Responding to the allegations, 2 Sisters Food Group said it had 'not been given enough time or detail to respond to the allegations' - describing them as 'false'.
The company's legal advisers, Schillings, wrote a letter saying: "Food safety and hygiene are 2SFG’s top priorities.
"To the extent that you have identified any shortcomings (which is not admitted), these could only be isolated examples which our clients would take very seriously, and they are investigating the allegations made."
You can read the full investigation here