A consumer organisation has called on food chiefs to name and shame retailers after a survey found that almost three fifths of fresh shop-bought chickens tested positive for campylobacter.
The food poisoning bug was present in 59% of birds tested, and in 4% of samples it was identified on the outside of the packaging, the Food Standards Agency (FSA) said.
Richard Lloyd, executive director of Which? said: "The FSA's survey reveals unacceptably high levels of campylobacter and they must now publish the names of the retailers so consumers are aware of the best and worst performing shops.
"Campylobacter is responsible for thousands of cases of food poisoning and the deaths of 100 people every year so much more must be done to minimise the risk of contamination at every stage of production."
The 12-month survey, running from this February to next February, is looking at the prevalence and levels of campylobacter contamination on fresh whole chilled chickens and their packaging.
The survey will test 4,000 samples of whole chickens bought from UK retail outlets and smaller independent stores and butchers. The new results are for the first quarter and represent 853 samples.
The FSA said that previous studies carried out into the prevalence of the bug had also shown around two thirds of raw poultry carries it.
Campylobacter is killed by thorough cooking, but is the most common form of food poisoning in the UK, affecting an estimated 280,000 people a year, and the majority of these cases come from contaminated poultry.
FSA chief executive Catherine Brown said: "This survey is an important part of the work we are doing to tackle campylobacter.
"It will give us a clearer picture of the prevalence of campylobacter on raw poultry sold at retail and help us measure the impact of interventions introduced by producers, processors, and retailers to reduce contamination.
"The chicken supply chain is looking at how interventions such as improved biosecurity on farms, rapid surface chilling, and anti-microbial washes can help reduce campylobacter.
"So when they take action and invest in interventions designed to make a difference, these survey figures will enable us to see if they really do make an impact.
"The low levels of contamination found on packaging, shown in the results released today, potentially indicate the effectiveness of the leak-proof packaging for poultry introduced by most retailers, which helps to reduce risks of cross contamination in consumers' kitchens.
"There is still a lot more to be done by all elements of the supply chain to ensure that consumers can be confident in the food they buy.
"As soon as we have enough data to robustly compare campylobacter levels in different retailers we will share that data with consumers."
The FSA said chicken is quite safe as long as consumers follow good kitchen practice:
Cover and chill raw chicken - Cover raw chicken and store at the bottom of the fridge so juices cannot drip on to other foods and contaminate them with food poisoning bacteria such as campylobacter.
Don't wash raw chicken - Cooking will kill any bacteria present, including campylobacter, while washing chicken can spread germs by splashing
Wash used utensils - Thoroughly wash and clean all utensils, chopping boards and surfaces used to prepare raw chicken. Wash hands thoroughly with soap and warm water, after handling raw chicken. This helps stop the spread of campylobacter by avoiding cross contamination.
Cook chicken thoroughly - Make sure chicken is steaming hot all the way through before serving. Cut in to the thickest part of the meat and check that it is steaming hot with no pink meat and that the juices run clear.