MPI deputy director of general regulation and assurance Scott Gallacher today said the ESR reports were far from definitive and further investigations were required.
"It was not able to pin-point the type of lettuce, or the product, or the brand, or anything else, nor could it actually pin-point the distribution chain or the supermarket."
Following a survey involving 96 people affected by the illness, an association with lettuce had been established.
However, it was linked to open-ended questions asking respondents to recall what they had eaten, Mr Gallacher said.
The ministry was not currently asking consumers to avoid any food products, he said.
The outbreak peaked in September and no new cases had been confirmed since September 30, Mr Gallacher said.
"I'm working with the Ministry of Health, because they're the ones who commissioned the report and both of us are now working so we can release those reports within the the next couple of days."
A Ministry of Health spokesman confirmed the report was due to be released later this week.
A spokeswoman from Food Safety Minister Jo Goodhew's office this afternoon said the minister had nothing to add to what the Prime Minister John Key said yesterday.
Mr Key yesterday said MPI was dealing with the outbreak as best it could.
"You wouldn't want them jumping to conclusions in either naming products, naming suppliers or naming supermarkets when it's not exactly clear what is the particular product that is causing these tummy bugs.
"I know there's a lot of speculation about what it might be, but until the Ministry [for] Primary Industries knows exactly what the product is and who's responsible, then they need to continue to take the course of action that they are."
Foodstuffs yesterday confirmed two of its products -- Pams Fresh Mesclun Salad Lettuce and Pams Fresh Express Lettuce -- were named in one of the ESR reports.
The products were traced back to three paddocks on one farm but were now past their use-by dates and no longer on shelves. Remaining Pams bagged lettuce products were safe for normal consumption, the company said.
Foodstuffs was now also undertaking its own independent audit and was confirming its farms were free from any possible contaminants prior to replanting.
Foodstuffs spokeswoman Antoinette Shallue said the products had all come from one farm based in the upper-North Island, but declined to specify its location.
No other products stocked by Foodstuffs were mentioned in the report, Ms Shallue said.
A spokeswoman for Progressive Enterprises -- owner of the Countdown chain of supermarkets -- said no products stocked by them were named in the ESR report.
New Zealand's largest lettuce grower LeaderBrand also confirmed to the Gisborne Herald that none of their products had needed to be recalled.
