The outbreak of a virulent form of pneumonia which is claiming lives around the world has been traced to a Hong Kong hotel.
The outbreak has been traced to Hong Kong's Metropole Hotel
An infected medical professor from southern China is thought to have carried the flu-like disease to Hong Kong's Metropole Hotel where six other guests contracted the illness.
The findings of Hong Kong officials increase suspicions that the illness is related to an earlier epidemic in China's southern Guangdong province which infected more than 300 people and killed five.
The World Health Organisation has confirmed nine deaths from the disease dubbed Severe Acute Respiratory Syndrome (Sars) and puts the number of worldwide cases at 264.
Most of the cases are in Hong Kong, Vietnam and Singapore.
The United States has identified 11 cases of the virus involving people who had travelled to Asia. Tests are also being carried out on two British men who have returned from Asia.
Scientists in Hong Kong say a virus from the paramyxoviridae family, which are responsible for conditions such as mumps and measles, is responsible for the respiratory illness.
They say the virus spread to medical staff and relatives who had close contact with the victims and that it also infected guests staying at the Metropole Hotel in the Kowloon district at the same time as the professor.
A hotel guest, a 78-year-old Canadian woman died on returning home.
The ninth floor of the hotel is closed
Others who contracted the disease had either visited or stayed on the hotel's ninth floor between 12 February and 2 March, according to the Hong Kong Health Department director Dr Margaret Chan.
"Perhaps they all stood outside the elevator at the same time and someone sneezed or coughed," she said, reports AP news agency.
But some have questioned whether the virus could have been spread through the hotel's air-conditioning system.
"It would suggest that it spread through the air-conditioning system, but you can't rule out person-to-person contact, since you don't know if they were even in the same room together," president of the American Society of Microbiology Ronald Atlas says.
"Everything suggests that it is airborne."
The hotel is still open but the ninth floor has been closed for sterilisation.
Guests wearing masks could be seen checking out of the hotel.
More work is needed to establish whether the virus is a new strain and whether it is curable, according to the doctors from the Chinese University of Hong Kong and Prince of Wales Hospital.
Tourists are checking out of the hotel
But a university spokeswoman told BBC News Online that the discovery indicated that the treatment being given to patients suffering from the pneumonia in Hong Kong - the hardest-hit area - was the right kind.
'World health threat'
The WHO has described the illness as a "worldwide health threat" and issued a rare emergency warning after cases were reported on three continents, with more suspected in other parts of the world.
However, the WHO believes prompt action by local health authorities appears to have limited the spread in Europe and North America.
Dr David Heymann, WHO executive director of communicable diseases, said: "The outbreak, we feel, is on its way to containment at least outside of Vietnam and Hong Kong, and China if it is linked."