25% of food tests show unsafe levels of bacteria

The worst offenders in the microbiological surveillance were meat and related products, where out of 1720 samples, 455 (26.5%) were found unsatisfactory.

Significant levels of pathogens were also found in cakes and confectionery (33.5% of 236 samples) and, perhaps surprisingly, herbs and spices (62.5% of 80 samples). One sample of fresh herbs was found to be contaminated with salmonella.

Hugh Pennington, professor of microbiology at Aberdeen University, said: "Many herbs and spices are coming from places where the hygiene practices are not of the same level that we have here.

"The issue with herbs is that they are mainly ready to eat, you don't cook them, you tend to sprinkle them on your food and put little or no heat in them."

Salmonella was found in three samples of raw chicken. No e-coli was detected in any of 164 samples submitted, although the presence of the campylobacter organism - the most common cause of infectious tummy bugs - was picked up in 83 samples of raw chicken, two samples of raw liver and two of fresh lamb.

Mr Pennington added: "Meat is less of a problem in a sense as you cook it. It is safe to assume that all meat has bacteria on it. You can't slaughter an animal without getting some manure on the meat.

"Everybody does their best in this country to get the bugs to a minimal level but lots of bugs get on it during the slaughtering process. The best thing the public can do is to go to a shop they trust."

FSAS stress the results do not provide a general reflection of the quality of food on offer, as the tests are carried out on products which carry a higher risk to health and not at random.

FSAS published the results yesterday. Chemical tests were also carried out on 6422 foodstuffs to identify contamination, presence of additives and accuracy of food labelling.

In the chemical surveillance, 21.6% samples were found to be unsatisfactory - an increase of 2.4% on last year with meat and meat products and prepared dishes giving the highest cause for concern.

A spokeswoman for FSAS said: "Unsatisfactory results do not always indicate the samples could present a risk to health. Where unsatisfactory results were obtained, the authorities would have acted immediately to ensure improvements were made.

"Salmonella and Campylobacter were only detected in a small proportion of foods, all of which were raw in nature. With the exception of one sample, all of these were raw meats that would have been cooked thoroughly prior to consumption.

"Salmonella was detected in a single sample of raw herbs. Again, because this product was raw, it would be expected to have undergone some cooking prior to consumption.

"Furthermore, if enforcement authorities had considered this sample to be a risk to public health they would have acted immediately and taken the appropriate action."

Chefs take on shops over chicken

Chefs Jamie Oliver, Gordon Ramsay and Hugh Fearnley-Whittingstall are taking on the nation's eating habits and major supermarkets in a Channel 4 show announced yesterday.

Oliver, 32, wants viewers to face the realities of industrial chicken production and has already held meetings with Sainsbury's, the supermarket he advertises, on the issue.

River Cottage star Fearnley-Whittingstall, 42, sets up his own intensive farm to see for himself how chickens are fed in artificial conditions to arrive on dinner plates in just 39 days. The chef, who breaks down in tears at the sight of his chickens, also challenges all supermarkets to go free-range.

Fiery chef Ramsay, 41, will demonstrate how to cook a healthy meal by asking viewers to do just that, live, after telling them what ingredients to buy.

Channel 4 said the issue of industrial chicken production was one of Oliver's "big, big passions".