A fifth of beef sold as "local" or "British" in pubs and restaurants in the south-west actually comes from abroad.
An undercover investigation, carried out by the BBC, revealed that beef in eight out of 40 tested venues was not even British despite claiming to be so.
The BBC took samples for DNA testing and found that eight were in fact from a humped back zebu, which only exist in South America and Africa.
Jilly Greed, who represents the National Beef Association in south-west England, told the BBC: "It's a great big con.
"It's pure exploitation of consumer demand for real local food - and until there's a properly audited trail through the hospitality industry, the situation is only going to get worse."
There is a loophole in current legislation, which means, for example beef in a pie could be Brazilian but as the pie is processed and made in Britain, it can be labelled as British.
"The labelling regulations are really complicated, especially for pre-packed and pre-prepared food," said Sarah Appleby, head of the imported food division at the Food Standards Agency.
"And I think this is an area where perhaps we could provide some more information to consumers to help them make the choices that they want to."
Trading Standards told the BBC it believed the situation was not confined to the south-west region.