New York - The United Nations has taken steps to lead the fight against the sudden outbreak of swine flu, mobilizing its agencies to help countries where cases have been verified, UN Secretary General Ban Ki-moon said Monday. "The UN system is responding, quickly and effectively, with the director general of the World Health Organization, Margaret Chan, taking the lead," Ban said.

"We are concerned that this virus could cause a new influenza pandemic," Ban said. "It could be mild in its effects, or potentially be severe. We do not know yet which way it will go. But we are concerned that in Mexico, most of those who died were young and healthy adults."

Ban warned that if WHO were to upgrade its alert to a pandemic level, countries around the world should show global solidarity. The WHO emergency committee is meeting Tuesday to determine any change in the level of global alarm.

Swine flu was first reported in Mexico, and confirmed cases have been found in the United States, Canada, Spain and New Zealand.

More than 149 people in Mexico have died of an influenza-type illness, but only 26 cases have been confirmed as a result of swine flu, according to WHO's investigation. More than 1,000 people have been hospitalized there.

In the US, 40 cases have been confirmed so far, but none have been fatal.

The WHO has set up an emergency committee at its headquarters in Geneva to lead the fight against the flu and was discussing whether to raise the disease to a pandemic level as it is spreading to more countries. (dpa)