While doctors would not identify the disease, they say the deadly respiratory illness sweeping through Asia and the world comes from a class of viruses known as paramyxovirus.

This family of microbes causes measles, mumps and canine distemper, as well as several respiratory diseases in young children and a variety of mammals and birds.

Hong Kong authorities unveiled their clue in solving the outbreak on Wednesday after Germany and Taiwan said they had pinpointed a similar virus. The World Health Organization (WHO) has been asked to verify the findings.

A swathe of countries across the world — among them Singapore, Canada, Taiwan, Australia, Britain, Brunei, Spain and the United States — have reported suspected cases of the disease.

On Wednesday the mystery virus appeared to have jumped to China's capital Beijing, as well as to Japan, Romania, Belgium, Finland and France.

So far 14 people have been killed by the virus, dubbed Severe Acute Respiratory Syndrome (SARS), and more than 500 have been infected.

The WHO raised the alarm over the weekend, issuing a rare alert over the disease but stopping short of advising people against traveling.

In their first global warning in 10 years, the WHO said they were worried about the "atypical" nature of the pneumonia, which appeared resistant to antiviral drugs and antibiotics.

The illness is believed to have originated in southern China, a region with a history of strange viruses, partly because people are encroaching