Twelve confirmed and 57 probable cases of E. coli have been linked to a restaurant in north Belfast, health authorities say.
The diners were struck down after eating at Flicks in Cityside Mall, York Street, in the last three weeks.
Management at the restaurant have voluntarily closed the premises and are co-operating with an investigation by the Public Health Agency (PHA) and environmental health officers from Belfast City Council.
The PHA has advised that anyone who ate at Flicks since September 24 and has symptoms of diarrhoea and/or abdominal pain should contact their GP urgently for medical advice.
The agency has revealed that four cases of the same E.coli O157 strain were linked to the restaurant in August. But it said subsequent tests in the restaurant at that time were negative.
Further environmental health inspections were conducted after those incidents, all of which were satisfactory.
The agency said it was examining whether the current outbreak was linked to the August instances but it was too early to confirm either way.