The Australian authorities closed a primary school for the rest of the week after two pupils were confirmed to have contracted the virus, a local newspaper said on Thursday.

There have been now six confirmed cases in Australia as Health Minister Nicola Roxon says she expects the number of cases to rise across the country.

"The situation is developing quite quickly and I suspect that later in the day there will be more cases to add to that number," she said.

Roxon said obviously closing the school is going to be an action that is going to inconvenience a number of parents, however, it is one of the steps that's being taken to try to contain and stop it becoming a disease that is widespread.

Three boys from one family tested positive to the AH1N1 virus on Wednesday, a week after they returned from a family holiday in Los Angeles. Two of the brothers attend the school.

Principal of the Clifton Hill Primary School sitting in Melbourne's inner north, Geoff Warren said Thursday morning the school, and state health and education departments, had taken the decision Wednesday night to close the school.

Warren said it was unlikely other pupils had been exposed to the virus.

"The concern is there," he said, "It's at a low level to be honest, but we need to be extremely cautious in this sort of situation, with the discussions worldwide about the potential for a pandemic from this," Warren said.