More than a fifth of meat sample tests in 2017 found DNA from animals not on the labelling, this was revealed following a BBC Freedom Information request to the Food Standards Agency (FSA).
Out of 665 results from England, Wales and Northern Ireland 145 were partly or wholly made up of unspecified meat. The samples were taken from 487 businesses, including restaurants and supermarkets.
In total 73 of the contaminated samples came from retailers – including three supermarkets. A further 50 came from restaurants, while 22 originated from manufacturing or food processing plants.
The samples were taken by Local authorities from businesses in their area before sending them to laboratories for analysis. The results were then submitted to the FSA.
The FSA said the levels were consistent with "deliberate inclusion" – but added testing had targeted those businesses suspected of "compliance issues".
Lamb was the meat most likely to contain traces of other animals’ DNA, followed by beef and goat. In total 77 of the contaminated samples came from lamb, 29 from beef, 19 from goat, 18 from pork/ham, one from duck and one from ostrich.
Some samples contained DNA from as many as four different animals, while others contained no trace of the meat that appeared on the product's label. Cow DNA was the most commonly-found contaminant, followed by pig, chicken, sheep and turkey.
The most commonly contaminated meat product was mince meat, while sausages, kebabs and restaurant curries also featured prominently. In total 41 of the failed samples came mince meat, 31 from kebabs, 23 from curries, 20 from sausages, 12 from goat meat and eight from burgers.
An FSA spokesman said it was up to the relevant local authorities who procured the samples to lead individual investigations and take "appropriate action" such as prosecutions.He added the results were "not representative of the wider food industry".
However, a clear picture of the wider food industry is not readily available as less than half of local authorities actually submitted meat sampling data to the United Kingdom's Food Surveillance System – part of the FSA – in 2017.
Some councils may have focused their food testing priorities "in areas other than meat substitution", the FSA said – adding that others may have carried out tests later in the financial year.
Substitution of expensive meat with a cheaper product is a common reason behind food fraud.
This latest data comes five years after the horsemeat scandal, when processed beef products sold by a number of UK supermarket chains were found to contain significant amounts of horse DNA.
While none of the 2017 samples contained horsemeat, the lack of transparency surrounding the quality and origin of meat products in the UK has raised concerns.