MOSCOW, May 1 (RIA Novosti) - The World Health Organization (WHO) has officially confirmed 331 cases of influenza A (H1N1), the technical name for the virus commonly known as swine flu, in 11 countries.

The United States has so far reported over 160 laboratory confirmed human cases in 19 states, including one death. Mexico has reported 358 human cases of infection, including 15 deaths.

The difference in some reported figures and those of the WHO could be down to the fact that not all countries have had all their cases confirmed by the global body.

Laboratory confirmed cases with no fatalities were reported in Austria (1), Canada (34), Germany (3), Israel (2), Netherlands (1), New Zealand (3), Spain (13), Switzerland (1) and the United Kingdom (8).

The WHO raised its alert level for a swine flu pandemic from 4 to 5, one step short of a full-scale pandemic on Thursday.

Although the illness has so far claimed few lives, the outbreak has sparked a number of dramatic media reports suggesting future death tolls "could" be in the tens of thousands or even millions.

The global health body also said well-cooked pork and pork products carry no risk of infection from the virus.

The head of Russia's Flu Research Institute said in an interview with RIA Novosti on Thursday that Russian scientists could create a vaccine to combat swine flu in three months.