New Zealand says it has at least three confirmed cases of swine flu among a school group that had recently visited Mexico and was expecting more.

Minister of Health Tony Ryall says a World Health Organization laboratory in Australia had tested three samples out of 11 and confirmed they had the H1N1 flu strain.

[Tony Ryall, Minister of Health]:
"I am advised that they selected four of the best samples of what I am told is very delicate genetic material to analyze. One of the samples is still being processed, the remaining three samples are positive for swine flu. Officials have informed me that is sufficient to indicate that swine flu is the cause of the illness experienced by Rangitoto group."

Tests on a fourth sample were under way, but the three positive tests are being taken as an indication the others had also contracted swine flu.

Ryall says all those affected appeared to have only mild symptoms and have been responding to treatment.

The ten students and one teacher were from a party of 25 from an Auckland secondary school, and came down with flu-like symptoms after returning from a three-week visit to Mexico last weekend.

The affected students and teacher had been in quarantine and treated with medications since Sunday.

In addition to the confirmed cases, New Zealand was also monitoring another 43 people for possible signs of swine flu. Earlier the number had been put at 56.