Staff from Auckland Regional Public Health were contacting those affected and informing them of the results. All are understood to be recovering at home.

Those affected will continue to receive the anti-viral drug Tamiflu and will remain in home isolation.

All 356 passengers on the flight into Auckland on Saturday with the Rangitoto College group had been urged to stay at home in quarantine. Officials said they have traced all but 18 passengers on the flight and they are being given Tamiflu.

The New Zealand government has asked airlines to make sure a statement providing advice and information on swine flu is read out on all incoming flights to New Zealand.

Health Minister Tony Ryall Ryall said the measure was in response to the increasing international spread of the potentially fatal virus. In addition, the Health Ministry has requested that a travel health notice be given to all incoming passengers on arrival.

The New Zealand government has warned against non-urgent travel to Mexico.

The government said a further 43 people with flu-like symptoms were being tested for influenza A, which may point to swine flu.

Officials said people who have traveled to Mexico or North America recently and has flu-like symptoms should phone their family doctor, but others with such symptoms have normal winter illnesses.

The Ministry of Health said people who have traveled to North and South America in the past fortnight should contact the health authorities.

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Editor:Yang Jie