Cadbury could find itself facing a series of lawsuits after health officials yesterday said contaminated chocolate made by the firm was the likely cause of a salmonella outbreak.
The Health Protection Agency said it had found that 13 of the 15 people it had traced who had been infected with the rare salmonella montevideo strain had eaten Cadbury's products.
No other food products or brands were found to have been eaten in all the cases.
The HPA launched its investigation after a surge in cases of the illness was noticed in March. The number of cases tailed off in June, which coincided with the recall of millions of Cadbury's chocolate bars.
A spokeswoman for the HPA said consumption of the Cadbury chocolate product was the "most credible" reason for the infections.
The HPA presented its findings to the Salmonella Montevideo Outbreak Control Team, which is made up of representatives from the HPA, the Food Standards Agency, Defra and selected local authorities.
A statement issued by the HPA said: "After carefully considering all the available evidence, the OCT concluded that consumption of products made by Cadbury Schweppes was the most credible explanation for the outbreak."
Cadbury had come under fire after it emerged the company had been aware since January of positive tests for salmonella contamination among a sample of its products, but did not tell public health authorities or consumers until June.
Bosses insisted the firm's products were "perfectly safe" when they ordered the recall.
But an investigation by the OCT showed the strain of salmonella montevideo in samples taken from Cadbury's factories matched the one which caused the outbreak.
Cadbury's blamed the contamination on a leaking pipe at one of its main factories in Marlbrook, Herefordshire.
The firm said in a statement yesterday: "We're sorry to hear that people have been unwell. We've already announced that we have changed our protocol because we understood that the consumers' desire for no risk at all is paramount. Any product showing any traces of salmonella will be destroyed."
Lawyers said the OCT's conclusion could prompt people to come forward and launch legal claims against Cadbury.
David Standard, spokesman for law firm Irwin Mitchell, said: "Confirmation of the causal link between the Cadbury's products and this rare and serious form of salmonella mean that the case strengthens for those people willing to take legal action.
"We believe that this will cause more people to come forward."
Irwin Mitchell is already investigating whether it can make a case against Cadbury on behalf of Catherine Henderson.
The 62-year-old from Larne, Co Antrim, was hospitalised after contracting salmonella allegedly as a result of eating a Caramel bar.
Herefordshire Council and Birmingham City Council are both investigating whether Cadbury failed in its duty to inform the Food Standards Agency if it believed a product on sale could be "injurious to human health".
The FSA has already rapped the Birmingham-based food company saying it used "unreliable" methods which may have underestimated the level and likelihood of contamination.
Andrew Tector, head of Environmental Health and Trading Standards at Here-fordshire Council, said if the contamination could be proved to have caused illness it would make prosecution more likely.
"It depends on the strength of the link," he said. "An investigation is also under way to find out whether hygiene regulations were breached, and four 'clean up' notices have been served on the Marlbrook plant."