Hong Kong - Health officials investigating a spate of food poisoning cases in luxury hotels in Macau on Tuesday were trying to find hundreds more boxes of contaminated oysters.

The outbreak in the Chinese gambling resort has been traced back to a batch of 1,500 contaminated boxes from a Hong Kong seafood exporter.

More than 100 people fell sick last week at the Venetian casino hotel, the Sands Macau Hotel and the Hotel Golden Dragon after eating the oysters.

Dozens of victims were taken to hospital suffering from vomiting and stomach pains after contracting food poisoning.

Five hundred boxes of oysters have been seized from cold storage at the Hong Kong seafood company, but hundreds of others had already been sold in Hong Kong or exported to Macau or southern China.

Officials said they had traced some of the boxes of oysters, but hundreds more could not be traced and might already be on the menus of hotels and restaurants around the region.

Macau is a densely populated former Portuguese colony one hour's ferry ride west of Hong Kong. It attracts millions of gamblers and weekend visitors from Hong Kong, Taiwan and mainland China.

It is famous for its new Las Vegas-owned casino resorts and last year generated more gambling revenue than the gaming hotspot in the Nevada desert, according to industry figures. (dpa)