Cadbury's chocolate has been blamed to be the most likely cause of the salmonella outbreak which affected several people earlier this year according to the Government's health watchdog.
The Health Protection Agency has alleged that contaminated chocolate bars and Easter eggs were the "most credible explanation" for the increased food poisoning cases in the spring and early summer.
Three people, including a baby and a child, were treated in hospital.
Cadbury has been officially linked to these cases for the first time since the outbreak. The company had previously denied any connection with the outbreak.
The blow of the announcement was seen yesterday when shares in Cadbury Schweppes closed at 518p down 6p.
Routine, internal tests at a Cadbury factory in Marlbrook, Herefordshire, in January revealed the presence of the rare salmonella montevideo strain in chocolate crumb. Further tests on other Cadbury products revealed the presence of "low levels" of the bacteria in seven products such as Freddo bars and button eggs.
Even after these results Cadbury concluded that there was no health risk and continued to allow the contaminated chocolate into the shops.
However HPA investigations followed the unusual outbreak of salmonella Montevideo and its source was traced back to Cadbury in June. This led to the withdrawal of about one million products.
Health officials blamed Cadbury for using "out of date" tests for salmonella at its factories as well as not alerting authorities to the contamination for five months.
According to the health watchdog up to 37 of the 56 cases of salmonella montevideo that were reported between March and July were identical to the bacteria found in Cadbury's confectionery. In addition 13 infected people iin England and Wales recalled eating Cadbury products. Still another also reported eating confectionery but she could not remember which brand.
The profile of the victims and the even spread of cases around the country suggested a nationally distributed food brand was responsible. The number of cases of salmonella poisoning has reduced since the recall.
The agency said,"The OCT [outbreak control team] concluded that consumption of products made by Cadbury Schweppes was the most credible explanation for the outbreak."
Other chocolate bars have also been tested at the company's Birmingham headquarters over the past couple of weeks.
Cadbury blamed the contamination on a leaking pipe that had since been repaired. However it declined to say whether it accepted responsibility for the outbreak.
A company spokesman said: "We deeply regret that people have been unwell. We have changed our testing protocol and implemented new procedures."