But these powers are for use only when the country faces a health threat that can prove 'disastrous', such as an outbreak of a fast-spreading infectious disease with the potential to kill many people.

The minister would then declare a public health emergency.

Such emergency powers are necessary as the Health Ministry prepares for an attack that is more deadly than Sars, said its minister yesterday during the debate on amendments to the Infectious Diseases Act.

One possible disease that could trigger such a situation is influenza.

Mr Khaw Boon Wan said the 2003 Sars epidemic taught Singapore one lesson: 'Reacting to the epidemic will grant the disease a headstart which can prove disastrous.'

Sars killed 33 people.

But a bird flu pandemic could kill more than 100 million people, said Dr Lam Pin Min, speaking in support of the move. Dr Lam, an ophthalmologist, had lost friends and colleagues to Sars.

So while he understands people's apprehension in giving so much power to the minister, he said: 'Any unnecessary delay may result in the rapid spread of the disease, with unimaginable magnitude of lives lost.'

The minister agreed. Such a deadly outcome is not 'theoretical', he said, citing previous flu pandemics.

'Influenza spreads rapidly because its incubation period is short, about two days, and it is highly transmissible,' he told Parliament, which later passed the Bill.

That is why it is necessary to act first, act fast and act together before the disease spreads.

Non-Constituency MP Sylvia Lim, who was among five MPs who spoke on the Bill, suggested that Parliament, rather than the minister, should decide when the country is faced with a health emergency.

Replying, Mr Khaw said there will be a need for speedy action. He noted that during Sars, the Government had to seek urgent approval from Parliament to contain the outbreak.

He also told Madam Halimah Yacob (Jurong GRC) that Singapore is not the first country to give such powers in an emergency.

Since the Sars outbreak, Britain, Western Australia and New Zealand have also changed their laws, to let action be taken without seeking approval from the legislature.

But the minister promised not to be trigger-happy: 'We know that these are drastic measures and we will use them only when absolutely necessary.'

Besides, there are safeguards, he added. A public health emergency can last for only 14 days unless renewed.

The public must be told and the minister has to justify his decision to Parliament, which can annul his order if the House is not convinced.

However, the strongest deterrent, he said, is the fear that crying wolf could damage the ministry's credibility, so people will not react when a real emergency occurs.

On the other hand, a delay in sounding the alarm could cause many deaths.

So a decision must be made before all information is available, he said.

This was what happened in 2003, when Singapore closed Tan Tock Seng Hospital - one of its busiest hospitals - before Sars claimed its first fatality in Singapore.

salma@sph.com.sg