The new provisions will empower health officers to prevent people at risk of being infected or already infected from leaving Hong Kong, conduct temperature checks, and medically examine people arriving or leaving, whom they suspect of having bird flu.

In rules stated in the Quarantine and Prevention of Disease Ordinance and made before Sars, only an outbreak of cholera, yellow fever or the plague would qualify as diseases requiring such sweeping isolation measures.

An amendment to the Prevention of the Spread of Infectious Diseases Regulations in the ordinance would cover the influenza strains of H5, H7 and H9, extending the specific border-control measures established for Sars, a spokesman for the Health, Welfare and Food Bureau said yesterday.

The amendment will take effect tomorrow.

Yesterday, at a Legislative Council session, Secretary for Health, Welfare and Food, York Chow Yat-ngok, said Hong Kong had the responsibility under the International Health Regulations not to export pandemic flu.

'The important thing is to prevent those infected from leaving,' he said.

He did not think the use of footbaths at Chek Lap Kok for incoming passengers from outbreak countries to prevent the introduction of bird flu had any scientific basis. Japan announced on Tuesday it will use footbaths at four key airports, including Tokyo's international gateway at Narita.

Dr Chow dismissed suggestions that Hong Kong should ban importing eggs from infected areas.

Meanwhile, he has assured legislators that in the event of a pandemic, Tamiflu would be provided free to private hospitals and clinics because the 'safety of patients' is paramount.