In 2013 foods advertised as containing beef were found to actually contain undeclared or improperly declared horse meat.

In some cases the illicit horse meat made up 100 percent of the meat content.

Analysis that followed the scandal also found that 23 out of 27 samples of beef burgers also contained pig DNA.

A subsequent review into the integrity and assurance of food supply by Professor Chris Elliott recommended standardisation of food testing techniques across a network of laboratories.

Professor Richard Evershed, a biogeochemist at the University of Bristol, said uncovering scandals of a scale equivalent to the horse meat debacle was inherently challenging.

“How do you sample a system which is dealing with such huge volumes of any number of commodities?” he said.

“It’s extremely difficult.

“There are some extremely complex tools available to combat food fraud, but we probably have no idea of the scale of fraud because there is no routine testing.

“I feel it should be the responsibility of the suppliers and the purveyors, but I don’t see how that issue can be forced.