Almost three out of four fresh chickens sold in U.K. shops are contaminated with campylobacter, according to the latest results from a year-long survey by the Food Standards Agency (FSA).

Campylobacter infections are the most common form of food poisoning in the United Kingdom, affecting an estimated 280,000 people every year.

Over the past 12 months the agency has tested more than 3,000 samples of fresh whole chilled chickens and packaging. Cumulative results for samples taken between February and November 2014 reveal that 73 percent of chickens tested positive for the presence of the food bug and 19 percent tested positive at the highest band of contamination.

Overall, 7 percent of packaging tested positive for the presence of campylobacter. Only three samples in total tested positive at the highest band of contamination.

When the full findings of the survey are published in May they will include the results from tests of around 4,000 samples of whole chickens bought from U.K. retail outlets and smaller independent stores and butchers.

The FSA highlighted the success achieved by one retailer, Marks & Spencer, to reduce campylobacter on its chickens. The retailer recently implemented a five-point intervention plan which has resulted in a significant reduction in the number of the most highly contaminated birds.

"If one retailer can achieve this campylobacter reduction through systematic interventions then others can, and should," commented Steve Wearne, director of policy at the FSA.

Responding to the FSA report, Andrew Large, chief executive of the British Poultry Council, 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."