GENEVA - The World Health Organization on Saturday branded the outbreak of a new strain of swine flu "a public health emergency of international concern," following a meeting of its emergency committee.

In a statement, the Geneva-based UN agency said it was recommending that all nations "intensify surveillance for unusual outbreaks of influenza-like illness and severe pneumonia".

Health officials worldwide scrambled Saturday to contain an outbreak of swine flu that has killed as many as 68 people in Mexico, with WHO director general Margaret Chan warning that the virus had "pandemic potential".

"After reviewing available data on the current situation, committee members identified a number of gaps in knowledge about the clinical features, epidemiology, and virology of reported cases and the appropriate responses," the WHO statement said.

"The Committee advised that answers to several specific questions were needed to facilitate its work (but) nevertheless agreed that the current situation constitutes a public health emergency of international concern."

It added: "Concerning public health measures ... the director-general is recommending, on the advice of the committee, that all countries intensify surveillance for unusual outbreaks of influenza-like illness and severe pneumonia."