Nearly three-quarters of fresh chickens in supermarkets and butchers are contaminated with the potentially lethal food-poisoning bug campylobacter.
The cumulative results for samples taken between February 2014 and February 2015 show that 73% of poultry is contaminated with the bacteria, and 19% of chickens are heavily contaminated.
Poisoning with campylobacter is the most common cause of foodborne illness , with chicken being the prime culprit. Each year about 280,000 people are made sick by it, with many thousands being admitted to hospital as a result and around 100 people a year dying.
Asda had the worst results across the year, with 80% of its chickens contaminated, 30% of them heavily contaminated, and 12% of its poultry packaging contaminated on the outside.
A Guardian undercover investigation last year added to pressure on the industry when it revealed high levels of contamination and poor hygiene at leading abattoirs, including birds that had been dropped on the floor being recycled into the food chain, and breakdowns in machinery leading to pileups of guts and high-risk material.