Some 73% of fresh shop-bought chickens are contaminated with the food poisoning bug campylobacter, and almost a fifth have tested positive at the highest level, results show.
The Food Standards Agency's cumulative results from the first three quarters of its year-long survey of fresh chickens show that the overall rate of contamination has increased from 70% in November and 59% in August.
The proportion of chickens testing positive for the bug above the highest level of contamination, or 1,000 colony forming units per gram (cfu/g), has risen from 18% in November to 19%, while 7% of packaging tested positive - up from 6% in August.
Asda again sold the highest percentage of chickens contaminated with campylobacter at 78.9%, with 31.1% showing the bug above the highest level of contamination and 13% of packaging testing positive.
Cost of chicken to rise to tackle food bug
Just over three-quarters of chickens (76.2%) sold by Morrisons tested positive, followed by The Co-operative (75.6%), Marks & Spencer (72.2%), Waitrose (71.7%), Sainsbury's (69.6%) and Tesco (68.2%).
Individual figures for the discounters Aldi, Lidl and Iceland were not reported because their market share was based on 2010 figures and deemed too small, but the overall rate of campylobacter contamination among all retailers other than the major supermarkets was 76.9%.
The FSA said none of the retailers were meeting the target for reducing campylobacter.
The FSA's survey will test around 4,000 samples of whole chickens bought from UK retail outlets and smaller independent stores and butchers.
The full set of results is expected to be published in May.
Steps being taken
FSA director of policy Steve Wearne said: "We now know it is possible to make positive inroads in the reduction of campylobacter.
"Figures released today by M&S show that their intervention plan has resulted in fewer contaminated chickens on sale in their stores. If one retailer can achieve this campylobacter reduction through systematic interventions then others can, and should.
"Our survey is putting pressure on retailers to work with poultry processors to do more to tackle campylobacter. We want the industry to reduce the number of the most highly contaminated chickens as we know this will have the greatest impact on public health.
"Campylobacter is killed by thorough cooking, but it should not be left to consumers to manage the risk.
"It is the most common form of food poisoning in the UK, affecting an estimated 280,000 people a year. Poultry is the source of the majority of these cases, so the industry should be making every effort to ensure chickens are as free from campylobacter as possible before they reach customers."
UK 'leading the way'
Richard McDonald, chairman of the Acting on Campylobacter Together (ACT) board, said: "The UK is leading the way in the search for solutions to reduce campylobacter levels.
"We have learned a lot over the last five years about which interventions have the potential to make chicken safer. We must continue to work together to apply these successfully and help industry deliver the results we all want to see.
"The ACT board is central to this work and represents a forum where processors and retailers can come together to discuss their work to tackle campylobacter and results from the latest interventions. This collaborative approach will be essential as the focus shifts to application and delivery.
"Although the impact of industry interventions has not been seen in the results from the FSA survey to date, we look forward to seeing progress in the FSA's follow-up survey."
British Poultry Council (BPC) chief executive Andrew Large said: "We welcome the news that retailers and their suppliers are making significant progress, and hope that proven technology will be made commercially available across the sector.
"The BPC remains committed to collaborative working between industry, retailers and regulators, as we believe this is where long-term consistency will emerge. This joint effort is a complement to the creativity and investment we are seeing.
"We are pleased to see the FSA's commitment to solving this problem remains as strong as our own, and we look forward to being able to demonstrate good progress as we move through 2015."
Which? executive director Richard Lloyd said: "It's unacceptable that we're still seeing such high and rising levels of campylobacter in chicken.
"While four major supermarkets have made their action plans public - The Co-operative, M&S, Tesco and Waitrose - the remaining three have yet to say how they're planning to tackle this bug.
"People need reassurance that supermarkets are doing everything they can to make chicken safe. The remaining retailers must publish their plans and commit to action now before consumers lose confidence in them."
Huw Irranca-Davies, shadow food and farming minister, said: "Consumers will rightly expect that all retailers take this issue extremely seriously and put in place robust measures to tackle the industry-wide challenge of reducing levels of contaminated chickens.
"These disappointing results suggest that none of the retailers are achieving the joint industry target for reducing campylobacter.
"After the horsemeat scandal and the recent allegations of hygiene failings in the poultry industry we need a better plan to restore confidence in the food sector. Labour will make sure that a transparent Food Standards Agency puts the consumer first and is able to challenge the industry to improve standards."
Read more about food safety on AOL Money:
Tesco stores have UK's worst hygiene
Arsenic found in rice products
Cost of chicken to rise to tackle food bug