An E. coli outbreak linked to a Belfast restaurant has been described as "major public health crisis" by Northern Ireland's Public Health Agency (PHA).
The PHA said there are now 25 confirmed cases and 154 suspected cases of food poisoning following an investigation at Flicks restaurant at Cityside Mall.
Six people have been hospitalised since the start of the outbreak, but most have since been discharged.
Dr Michael Devine from the PHA said it was NI's worst ever E. coli outbreak.
The doctor, who is the PHA's consultant in health protection, said: "The further increase in cases is not unexpected as the incubation period for E coli is typically up to seven days. We expect therefore to see a further increase in cases as people continue to report symptoms and submit samples for testing."
Dr Devine said that over the past decade, the number of people affected in previous E. coli outbreaks in Northern Ireland had never exceeded 20.
The doctor told BBC Radio Ulster's Nolan Show on Tuesday that the agency was "not in anyway underestimating the scale of what we're dealing with here".
Eight children under the age of 14 are among the suspected cases to date, he said.
A separate E. coli outbreak in August affected four people who ate in the same restaurant on York Street.
At the time, the PHA and Belfast City Council environmental health officers carried out an investigation and all tests on the restaurant were negative.
The owner of Flicks, Michael McAdam, said there was "no definitive evidence" in August that the four people had contracted the poisoning at his restaurant.
"I would not dream of opening the doors of a restaurant if we were doing something wrong," he said.
"It would be commercial suicide and apart from that to endanger people would be ridiculous."
He added that hygiene in the kitchen met the highest standards.
"All of our books and health checks are up to date, staff training is all up to date. We have followed every rule and regulation. We take our job seriously and where this came from I have no idea," he said.
In the latest outbreak, the first case was reported to the agency on Tuesday 9 October and, two days later, the PHA had established that a total of four people who had eaten at Flicks had all been infected with E. coli.
Staff at the restaurant were informed and they voluntarily closed to the public at 18:30 BST on 11 October.
Dr Devine told the Nolan Show: "We are dealing with a major public health crisis with these cases and we must ensure that we prevent any preventable cases.
"There will be an investigation, there will be analysis of the results and if any link to the August cases is established then that will have to be looked into."
The doctor explained that in August, judgements had been made based on environmental inspections and the results of food samples tests which had indicated the outbreak "appeared to be contained at that stage".
"There were no further cases from mid-August until we were told about the case on 9 October, which suggested there was no ongoing issue at the restaurant in that time. You can appreciate that if there was an ongoing issue at any facility, you would expect cases to become apparent.
"The incubation period is typically three to five days, but can be up to 10 to 14 days", he said.
"But, in any event, we would have expected to see more cases associated with Flicks restaurant if there had been an ongoing problem."