The five men and three women developed diarrhoea, abdominal pain, vomiting and fever between 25 and 75 hours after dining in two groups at the Clipper Lounge in the hotel on Connaught Road Central on January 31 and February 2.

The Centre for Health Protection said four sought medical advice but none required hospitalisation. All were now in a stable condition.

A preliminary investigation found the affected diners, aged 28 and 29, had eaten raw oysters, salmon sashimi, crab legs and brown crab. Officials suspect the illnesses may be linked to raw food.

The centre is continuing the investigation.

It noted that food poisoning cases had risen sharply in recent weeks, climbing from an average of one per week in late December to four per week last month. Thirty cases have already been recorded since February.