* New Zealand says three confirmed cases of swine flu
* Health ministry says expects another eight to be confirmed
* A further 43 being monitored
(For full coverage of the flu outbreak, click [nFLU]) (Adds details, comment, background)
WELLINGTON, April 28 (Reuters) - New Zealand said on Tuesday it had 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 said a World Health Organisation laboratory in Australia had tested three samples out of 11 and confirmed they had the H1N1 flu strain.
"Officials have informed me that is sufficient to indicate that swine flu is the cause of the illness experienced by the group," Ryall told a news conference.
Tests on a fourth sample were under way, but the three positive tests were being taken as an indication the others had also contracted swine flu.
Ryall said all those affected appeared to have only mild symptoms and had been responding to treatment.
"All 11 are recovering at home," he said.
The ten students and one teacher were from a party of 25 from an Auckland secondary school had come 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 anti-viral drugs since Sunday.
Authorities have tracked down most of the 356 people who were on the same flight from Los Angeles as the infected students.
In addition to the confirmed cases, New Zealand was also monitoring a further 43 people for possible signs of swine flu. Earlier the number had been put at 56.
The people have shown flu-like symptoms and were being tested to see if they have Influenza A, which is linked to swine flu.
New Zealand has raised the alert level of its national pandemic plan and is screening all flights from North America.
The deadly swine flu strain has killed up to 149 people in Mexico and infections have also been found in the United States, Canada and Europe. (Reporting by Mantik Kusjanto and Gyles Beckford, editing by Andrew Marshall)