A Chinese virologist has warned of spreading deadly swine flu in China and India after Mexico announced the death toll of the outbreak rose.

"We are counting down to a pandemic," Guan Yi who helped fight SARS and bird flu said on Monday.

Late Sunday, Mexican Health Minister Jose Angel Cordova announced that the number of both suspected and confirmed fatalities from the flu has reached 103.

The number of cases under observation in Mexico has reached 1,614, up from 1,324, according to the minister.

Guan, a professor at the University of Hong Kong, said there would be many problems if swine flu reached China and India, "where populations are so dense and health infrastructure is still insufficient."

"When it goes into a place like China, there will be very high transmissibility among people," Guan noted.

The virus carries swine, avian and human DNA and the designation H1N1.

The US confirmed 20 cases in five states, saying that it will screen visitors arriving from infected areas.

Suspected cases were also investigated in Europe, the Middle East and Asia, and six new infections were confirmed in Canada.

Britain said it is monitoring closely the spread of swine flu as three potential cases had been reportedly found in the country.

Spain's Health Ministry also announced that the country is investigating seven possible cases of swine flu in four autonomous regions.

The World Health Organization said Monday that Asia is better prepared than other regions to handle the outbreak due to its experience dealing with epidemics such as SARS.

The spread of Severe Acute Respiratory Syndrome (SARS) in 2003 led to countries around the region screening air passengers, closing down schools, stockpiling anti-flu drugs and quarantining thousands of suspected cases.

The WHO earlier described the virus as a "public health emergency of international concern," urging all countries to intensify surveillance for unusual outbreaks of flu-like diseases.

AGB/DT