The global body says 12,720 new cases have been reported since Wednesday — about half of them in the United States.

WHO says Britain, Chile, Mexico, Philippines also reported large numbers of new cases.

Health experts say the number of cases reported to WHO is far below the figure of actual infections because many are mild and never diagnosed.

WHO is working on mathematical models to estimate the real number of infections.

According to the agency’s swine flu update Friday, the number of deaths increased by 50 to 382.

Most of the deaths occurred in the US.

World Health Organization head Margaret Chan added that the holding of the meeting in Cancun showed confidence in Mexico, which has been hard hit.

The WHO says most H1N1 cases are mild, with many people recovering unaided.

As the summit opened, the UK alone was projecting more than 100,000 new cases of H1N1 a day by the end of the summer.

As the peak of the flu season approaches in South America, some areas have declared a public health emergency.

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