London - Health authorities around the globe are beginning to suspect that the mysterious strain of pneumonia spreading from the Asia-Pacific may be a new microbe.

Ten people have died and hundreds more are ill with symptoms. The disease has spread rapidly to Europe, the United States and Australia.

Scientists in several countries have been working to identify its cause but have been unsuccessful so far, which health officials say suggests it could be a new micro-organism.

"As time goes by, that is increasingly likely, simply because so many people have run tests," said Iain Simpson, a spokesperson for the World Health Organisation (WHO).

"If it is something we knew about, we would almost certainly have identified it".

The WHO, which is co-ordinating the international response with the Centres for Disease Control and Prevention in the US, expects more people in more countries to become ill.

"But that does not mean there is a growing pandemic. It is better reporting," said another WHO spokesperson, Dick Thompson. "What we are seeing is that all certified cases are linked in some way to Hong Kong and Hanoi, except for the cases in Canada."

The illness, known as Severe Acute Respiratory Syndrome, has claimed two lives in Canada, two in Hong Kong and one in Vietnam. Five people have died in mainland China, although experts say it is unclear if these cases are related.

Most cases have been in populous Hong Kong, where 123 people are ill; Vietnam, which has reported nearly 60 cases; and Singapore, with 23 cases.

Suspected cases have been reported in Australia, Britain, Germany and the US.

The flu-like illness begins with a high fever, chills, cough and breathing difficulties and apparently shows some resistance to conventional drugs. Most of the people who have fallen ill are health workers or others who have had close contact with patients. - Reuters