By David Bottomley BBC, Singapore

Singapore's prime minister has said that unless the Sars virus is contained it could become the worst crisis the country has faced.

The number of people suffering from the flu-like illness is fewer than 200, but more cases are being diagnosed every day and fear of the virus is starting to hurt the economy.

Although Singapore is one of the worst-affected countries, a range of containment measures has been reasonably effective so far in limiting the number of Sars cases.

This is actually a crisis of fear Goh Chok Tong, Prime Minister

People with the virus and suspected sufferers are kept in strict isolation, and those who might have come into contact with sufferers are being kept under quarantine.

But still the number of cases goes up, and prime minister Goh Chok Tong, in a BBC interview, said that he was worried about the economic knock-on effect.

"This is actually a crisis of fear. People don't quite understand what it is, and if this doesn't come to Singapore and our social behaviour changes dramatically, the economy is going to be hit very badly," he said.

People's behaviour has already changed.

Shops and restaurants are reporting fewer customers, and the number of visitors to Singapore fell by 60% in the first half of April.

Already the government has cut its forecast growth rate by 1.5%.