The World Health Organization (WHO)warned Wednesday that the bird flu virus, which has caused an Asia-wide health scare, is likely to be far more serious than the severe acute respiratory syndrome (SARS).

"If the H5N1 (avian influenza) virus attaches itself to the common human flu virus and if it is then effectively transmitted, it has the potential to cause widespread damage," the Philippine Star daily on-line news quoted Peter Cordingley, spokesman of the Manila-based WHO Western Pacific Region Office, as saying.

At least three -- possibly 12 -- deaths in Vietnam since October have been linked to the virus which killed six of 18 people who fell sick in China's Hong Kong in 1997.

Cordingley said more deaths are expected in Vietnam due to the H5N1 virus. He said one of two young children with the flu symptoms was in a critical condition in hospital.

"This mortality rate is far higher than that of the SARS virus," Cordingley said.

"The common human flu virus is far more infectious than the SARS virus and can be spread by aerosol and not just through droplets as in the case of SARS virus," Cordingley explained.

Current evidence indicates that the H5N1 virus can spread from poultry to people but not easily from person to person.

Vietnam is currently battling to contain an outbreak of bird flu that has infected between one and two million chickens. Japan and South Korea are dealing with much smaller outbreaks of the disease.

Editor: Wing