Hong Kong imports about 150,000 live pigs a month, mainly from Guangdong province, and imported about 30,000 tonnes of frozen pork in 2004 from Sichuan alone, the Food and Environmental Hygiene Department said.

Pork from Ziyang and Neijiang - the two cities infected most by a mysterious disease - was banned from export by the state Monday. But the SAR government said frozen pork from other cities in Sichuan province will not be banned.

At least 80 people have been infected since June in the province after eating or being in close contact with sick or dead pigs. Nineteen people have died while 17 remain in critical condition from what is believed to be a stretococcus bacteria infection passed on from the pigs.

State media reported that the patients are from 49 neighborhoods in the cities of Ziyang and Neijiang. All patients displayed similar symptoms - including high fever, fatigue, nausea and vomiting - and became comatose when they developed bruises under the skin. Although medical staff at one of the hospitals had said the infection was caused by the pig disease, the Ministry of Health have yet to confirm that diagnosis and are still referring to it as an ``unidentified disease.''

Officials from the health and agriculture ministries were sent to Sichuan to investigate.

Infectious disease expert Lo Wing-lok said the SAR government should join in the investigation to better protect Hong Kong's interest.

``Uncommon situations warrant uncommon measures,'' Lo stated in an RTHK program Monday. ``It is really an uncommon situation where 17 people are dead from a pig disease. It is not confirmed if the infection was caused by the streptococcus suis bacteria yet.

``Other than receiving information through the usual notification system, the government could send people to Sichuan to see how serious the spread is, whether the pork supplied to Hong Kong is affected and to get more information before telling the public that Sichuan pork is safe.''

At the same time, Lo said the government should ban the import of frozen pork from the province to ensure the public remains confident in the safety of pork imported from other areas.

Since people who handle raw pork are at higher risk of being infected by the disease, Lo offered some tips.

``Frozen pork needs to be fully defrosted. Put it in the fridge overnight to make sure the inner part is thoroughly defrosted before cooking because otherwise, the inner part may not be cooked and bacteria may survive,'' he said.

Chilled Meat and Poultry Association chairman Kwok Shi-hing urged the public not to be fearful as frozen pork from the mainland is quarantined by the state before being exported and cross-checked by the Food and Environmental Hygiene Department before being imported in Hong Kong.

``The department can temporarily ban frozen pork imports from Sichuan and make up the shortfall from other provinces. It is acceptable to ban Sichuan import,'' Kwok said.

Assistant director (Food Surveillance and Control) Thomas Chung said frozen pork from the mainland is regulated and the meat comes from live and healthy pigs.

``Hong Kong is safe,'' he said. ``Frozen pork imported from the mainland bears a health certificate with details including from which city it has come.''

He said the food-safety risk is low because all the patients in Sichuan had been in contact with pigs or sheep. Nevertheless, the department will keep a close watch. However, he said the department will not be sending officials to the province at the moment.

Hong Kong's leading supermarket chains, ParkNShop and Wellcome, have stopped the sale of frozen pork from Sichuan.

``Although the government did not issue any guidelines on whether to stop selling or recall the pork, we decided to suspend selling pork from Sichuan for the safety of customers,'' Wellcome spokeswoman Diane Chiu said.

According to the Health, Welfare and Food Bureau, the mainland's General Administration of Quality Supervision, Inspection and Quarantine has confirmed that none of the registered pig farms that export pork, or their workers, are affected by the disease.

The mainland department also said the pork exported to Hong Kong is safe but, as a precautionary measure, all pork product exports from the cities of Ziyang and Neijiang are banned for now.

The Agriculture, Fisheries and Conservation Department has called on local pig farmers to monitor their pigs and notify the government if they, or the animals, fall ill.

State media also reported that mainland authorities have denied the mysterious disease is SARS or bird flu.

``I can assure you that the disease is absolutely not SARS, anthrax or bird flu,'' Zeng Huajin, a senior official with the Sichuan health department, told the China Daily.