An investigation is now being carried out on the University Medical Centre Utrecht's study, which was testing the effectiveness of probiotics at reducing infection.
The European Food and Feed Cultures Association (EFFCA), which represents manufacturers of probiotic strains, said it is paying " serious attention " to the study and is awaiting the official publication of the findings.
Researchers carried out the large study between 2004 and 2007, after smaller tests had shown probiotics could help reduce the rate of infection in the pancreas.
These were considered too small to convince doctors to use probiotics in all patients with this condition.
Two hundred and ninety-six patients with acute pancreatitis - a rare and very serious disease - took part in the study across 15 hospitals in the Netherlands.
Twenty-four died in the study group and nine died in the control group.
Because it was a double blind study - which means neither patients or researchers knew whether they were in the control or experimental group - the findings not emerge until the end of the trial.
Health investigators do not know the cause of the deaths, but have narrowed it down to three possible potentials: the use of probiotics on intensive-care patients; administering probiotics through feeding tubes into the intestine; and using the friendly bacteria in the acute phase of the disease.
The investigators have told colleagues not to use probiotics on patients who meet any of the three criteria under investigation.
No implications The probiotics used in the tests were supplied by Winclove, a Dutch dietary supplement company.
Winclove said it still has great confidence in the overall ability of probiotics to combat bacterial infections in the gut.
EFFCA reiterated the fact that acute pancreatitis sufferers have a high mortality rate, and said the study had "no implications" for the ordinary use of probiotics in food, beverage or dietary supplements.
A spokesperson said: " All the probiotic strains marketed by EFFCA members have a long history of safe use both in food and dietary supplements and have been assessed in terms of safety studies.
"To our knowledge, probiotic clinical studies had never resulted in the degradation of the health condition before.
On the contrary, many health promoting benefits from probiotics have been scientifically demonstrated."
Acute pancreatitis is defined by rapid inflammation of the pancreas and in about five per cent of case can be fatal if complications occur.
Approximately 2 in every 100,000 people in the UK have acute pancreatitis every year.