Asian airlines flew almost empty planes during the Sars outbreak

A medical researcher who was investigating the virus has been hospitalised, health officials said.

News that the man had recently returned from a conference in Singapore sent Asian airline stocks into a tailspin, with many down more than 2%.

Stock markets in Tokyo, Hong Kong, Taiwan and Singapore were all pulled lower on Wednesday morning as a result.

'Irrational disruption'

Shares in Singapore Airlines fell 2.6% in morning trade, while Japan's biggest carrier, Japan Airlines dropped 3.5%; All Nippon Airways shed 2.6%.

Cathay Pacific, the Hong Kong based carrier, saw its stock drop 2.36%. Stocks in China Eastern and China Southern were both lower in Hong Kong.

The region's major stock markets all felt the impact, although they stabilised by late morning as panic subsided.

In Taiwan, the Ministry of Finance said it was ready to support stock prices against "irrational disruptions" after the leading stock index fell steeply - down more than 2%.

Shares in Taiwan-based China Airlines, the airline used by the Sars patient to return from Singapore, had shed 3.6%, while Eva Airways dived 4.1%.

Tokyo's benchmark Nikkei index fell nearly 2%, though the weak dollar and upward pressure on the yen also played a role.

Singapore's Straits Times Index was 1.8% lower at the end of morning trade. In Hong Kong, the Hang Seng shed 0.7% but rallied in during the afternoon session. China's main stock indexes showed no ill-effects.

Asian airlines' finances are still recovering from the Sars outbreak earlier this year, which forced carriers to cancel many flights as travel into the region slowed to a trickle.

Traders said stock prices would recover fast if the infection proved to be an isolated case.

"The market is far more prepared this time and can rebound strongly if indeed the authorities confirm it is an isolated case," said Gabriel Yap of Kim Ong Asia brokerage in Singapore.

Sars killed over 800 people and infected as many as 8,000 in a world-wide outbreak earlier this year