One child from a South Auckland children's centre has so far tested positive for a probable case of swine flu after another from the same centre tested positive for the flu.
Eleven other children from the centre were suspected of having contracted the disease.
The children were tested after a one-year-old baby boy, enrolled at Tama Ale Eleele A'oga Amata, tested positive after returning from Melbourne on May 26 with his family.
He is now in isolation at his home with his family.
Further tests on the results of the child who tested positive for Influenza A will be conducted to confirm if it is swine flu, a Northern Regional Health Co-Ordination Centre spokeswoman said.
Tests from the other 11 children will be processed overnight.
Auckland Regional Public Health Service will work with staff and families of children enrolled at the Papatoetoe child care centre, she said. There were 37 children enrolled in the centre and seven staff members.
Families from the centre should call the Auckland 0800 FLU LINE (0800 358 5463) if they had any concerns or wanted further information, the spokeswoman said.
The Department of Health was also contacting people who had been sitting near the infant on the flight from Australia.
New Zealand now has 13 confirmed cases of swine flu.
People with flu symptoms who had returned from overseas in the past seven days were told to seek advice via phone, as turning up at a hospital or medical centre helped spread the virus.
Three new cases have been confirmed this week, and health officials are warning that cases are likely to increase given the huge rise in infections in Australia.
An advertising campaign started today in newspapers and on radio, airport posters and billboards to remind people about swine flu and how to limit its spread.
More than 100 people have died from swine flu worldwide, and 19,273 cases have been reported in 66 countries.
Australia reported 878 confirmed cases of swine flu as of 5am today, up from 634 a day ago.
