The number of infections in the United States rose to 65, Canada has 13, and new cases were also confirmed in Israel and New Zealand.

The United States, Canada and the European Union are telling people to avoid non-essential travel to Mexico, and Cuba suspended all flights to and from Mexico for 48 hours.

Travel companies were also staying away. Carnival Cruises cancelled stops at Mexican ports for three of its ships on Tuesday and Canadian tour operator Transat AT postponed flights to Mexico until June 1.

The World Health Organisation said a pandemic - a global outbreak of a serious new illness - is not yet inevitable but that all countries should prepare for the worst, especially poorer developing nations. 'They really get hit disproportionally hard,' said the WHO's acting assistant director-general Dr Keiji Fukuda.

One of the mysteries of the outbreak is why the virus has killed scores of people in Mexico while the cases outside the country have been relatively mild and no one has died. Experts say this may be simply a matter of where they have been looking to find it and officials say they expect to find deaths as the disease spreads.

A pandemic could snuff out fragile signs of economic recovery around the world as travel, trade and manufacturing output would all be hit. The last flu pandemic was in 1968, when 'Hong Kong' flu killed about 1 million people around the world.

Seven countries have confirmed cases of the swine flu and a dozen others have suspected infections. Mexico City is at the center of the outbreak and many residents are staying in their homes while schools, churches, cinemas and restaurants have all been shut down.

Airline share prices declined again on Tuesday on fears that they could experience a sharp drop in traffic. -- REUTERS