By Chris Choi, Jade Liversidge and Rupert Evelyn: ITV News
ITV News believes the biggest food investigation in Britain is about to get bigger.
The Russell Hume company supplied some of the country's best known food providers, including British Airways, Wetherspoon and Jamie's Italian.
So far, officials have only revealed that their enquiries concern 'use-by' dates.
Breaches of rules at Russell Hume were so serious and widespread, they triggered a mass recall of meat supplied to a string of big-name caterers.
But we understand there are also concerns about whether labels misled customers about the meat's country of origin.
Speaking to us anonymously, a former Russell Hume worker has made his accusations against the company public for the first time.
"Imported beef is a third less in price than British beef so there's an opportunity to make 30% more profit," he told ITV News.
"Its what the industry does and has been doing for a long time. Falsifying traceability of imported beef and making it into UK beef and then serving it to some of the biggest companies in the country."
The big companies that used Russell Hume meat have now switched supplier.
Many had ordered British beef. That's what they thought they'd got - and that's how they described it on their menus.
ITV News Consumer Editor Chris Choi on the impact on the industry
The former worker we have spoken to claims sometimes it was mislabelled.
"You'd make sure you had enough beef to service the orders whether it was Botswana, Namibia, Australia and we will make it British," the worker said.
We asked Russell Hume about the accusations made by our interviewee.
The meat firm told us: "As the FSA states on its website, its investigations into Russell Hume are related to procedures and processes relating to use-by dates. We do not recognise the allegations made in the programme, but in any case we continue to work closely with the FSA in resolving this matter."
The company says it supplies "premium meat products from the British Isles and around the globe .. via reputable sources and only from high quality markets", and that it has " a long and previously unblemished record".
Prominent figures in the beef sector say accusations about 'use by' dates must be thoroughly investigated and ITV News has been told there is a known problem in the industry.
Chris Mallon, Director of the National Beef Association, told us: "Most of the industry is reputable it is only a minority who are causing a problem to those who are abiding by the rules that are set. The food chain depends on trust and anything at all that takes that away is going to be a problem."
The Food Standards Agency said in a statement: "Our investigation into Russell Hume is related to a number of issues including concerns about procedures and processes around use by dates.
"The Food Standards Agency and Food Standards Scotland took action to stop production at Russell Hume sites last month and affected products have already been withdrawn.
"It is now in the interests of consumers for us to pursue our investigation fully which could include the possibility of criminal proceedings and not to jeopardise it by commenting any further on allegations.
"We have also jointly announced an industry wide review of meat cutting premises and cold stores in the UK."
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