Speaking at an open meeting of the UK Veterinary Residues Committee, agriculture representative Tim Brigstocke said that with the UK being only 63 per cent self-sufficient in food, the country relies heavily on imports.

And these imports have to be sampled and checked to ensure they do not contain any harmful residues from veterinary medicines or antibiotics.

He said that the non-statutory programme for sampling and testing that takes place at UK ports had never been so important.

"The non-statutory programme is extremely important particularly for the surveillance of raw beef and farmed fish. Sampling imports has never been more important," Mr Brigstocke said.

The programme samples food product brought into the UK from outside the EU. All products produced or transported across borders within the EU have free market access.

In 2011, the non-statutory surveillance programme took 1,228 samples last year and carried out 4,913 analytical tests on them.

The sampling and tests found a total of 12 non-compliant residues including nitrofurans in warm water crustaceans and avermectin in corned beef.

When any such residues are found, the chief veterinary officer is alerted and the Food Standards Agency carries out a full risk assessment.

However, Mr Brigstocke said the there has to be concerns because of the number of samples that are being taken and the spending cuts that are expected.

"Surveillance must be maintained and coordination improved to strengthen non-statutory surveillance," said Mr Brigstocke.

"We are very concerned about this whole area."

Mr Brigstocke added that the authorities could be helped if they could access the information produced by tests taken by food retailers and manufacturers, who are importing the products into the UK.

This year Jon Averns, the Port Health and Public Protection Director for the City of London said that a total of 820 samples have been taken and 1,710 analytical tests had been carried out.

The number of samples taken is on an average of 54,000 consignments that enter the UK each year.

Mr Averns said: "We need consistency of enforcement throughout the EU, because once the product is in the EU there is free circulation of products."

While there is concern over the potential thoroughness of inspection of good imported into the UK, the statutory surveillance of food from animal origin produced within the UK is showing good compliance with the regulations.

Last year a total of 32,723 samples were taken from food products produced in the UK and 36,449 analytical tests were carried out.

A total of 175 residues were detected and 159 were hormonal residues or thyrostatic substances that are banned but some of which occur naturally. Of the other 16 residues, 13 occurred because of incorrect use of the veterinary medicine. The surveillance found that in three cases the residues were phenylbutazone - two in calves and one in a horse.

"While we do not eat horsemeat in this country, we do export it," said Mr Brigstocke.

He added that the committee is concerned about the use of phenylbutazone for horses because of the potential contamination to the meat for export.

Many of the causes of residues above the maximum residue levels being found in food products of animal origin are down to either incorrect administration of the drug initially, the withdrawal periods being too short or through the administration of illegal drugs.

Often the problems occur in paperwork that has either been in incorrectly filled in or because an animal that has been sent for market has been sent to slaughter too soon because of ignorance over the drugs that have been administered and what the withdrawal period should be.