Foodstuffs has confirmed two of its Pams products, Mesclun Salad Lettuce and Fresh Express Lettuce, were named in a report listing possible sources of a food poisoning epidemic.
There have been 127 confirmed cases of yersinia pseudotuberculosis and 38 people have been hospitalised as a result of the stomach bug.
Environmental and Scientific Research (ESR) reports have been provided for the Ministry for Primary Industries (MPI) updating the possible source.
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However, the ministry is refusing to release the list.
MPI deputy director of general regulation and assurance Scott Gallacher said it had been working to locate the source of the outbreak, but the information was preliminary and far from conclusive.
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Canterbury Medical Officer of Health Dr Alistair Humphrey said health agencies announced last week bagged lettuce and bagged carrots appeared to be the source of the problem after receiving the ESR analysis.
It produced "a clear result", however MPI decided the "producer and/or retailers would not be named and shamed".
"It is a conflict of interest. They [brand] could have been named but they were not. MPI has to serve the industry as well as the New Zealand public in terms of their health," Dr Humphrey said.
- additional reporting Teuila Fuatai