Twelve people were taken to hospital yesterday when they suddenly fell ill after eating in Aberdeen's Exhibition and Conference Centre.

Ambulance, police and the fire service were called to the venue after the six men and six women were struck down with vomiting and diahorrea. The victims, who had been lunching in the venue's gallery area, were admitted to hospital and an investigation was launched into the cause of the incident.

The 12 were all clients using the AECC facilities yesterday. Food is served to clients in the gallery area at lunchtime and food poisoning has been identified as one possible cause.

It is understood a tuna dish was being investigated as a possible source of the problems.

A spokesman for the AECC said that all the emergency services were alerted when the victims took ill because at that stage there was no indication of the cause. He said it was possible that it could have been a chemical reaction in the gallery area but that had subsequently been ruled out.

Nine ambulances and eight police cars attended along with Grampian Fire and Rescue Service who carried out tests to determine if there was any airborne contamination which proved negative.

AECC acting managing director Brian Horsburgh said the symptoms of those who took ill were similar to those of an allergic reaction.

"A number of people had a reaction after they had lunch which made us suspicious that it might have been something with some food."

Rock band the Stereophonics were scheduled to perform at the AECC last night but Mr Horsburgh said the concert and arena sections were unaffected. Last night a spokesman for NHS Grampian said that following assessments of the 12 patients all were in a satisfactory condition.

Two patients were kept in overnight for observation but the others had been discharged and no further admissions are expected. He said Accident and Emergency had been able to manage the incident as part of their normal daily workload.

NHS Grampian's public health department will meet with the city's environmental health department and Health Protection Scotland this morning to investigate the cause of the illness.