WELLINGTON - Swine flu could infect more than a million New Zealanders over two years, health officials said Friday, as the world's first global pandemic for 40 years was declared.

"It's inevitable with the increasing number of international cases of swine flu that we will end up with higher numbers in New Zealand and greater spread in the community," Health Minister Tony Ryall told a news conference.

But he added there was no reason for alarm because the country was well stocked with antiviral drugs which had proved effective in treating the symptoms of influenza A (H1N1).

Deputy director for Public Health Darren Hunt said people lacked immunity to the new virus strain and the high infection estimates were not surprising.

"The upper level is of course you might end up with 20 or 30 percent of the (4.2 million) population with swine flu, but we don't know, and that's why New Zealand is running its very tight containment strategy," he said.

The Health Ministry said Friday 34 New Zealanders were confirmed to have been infected with swine flu, an increase of seven from the day before.

Most early cases were among people who had travelled to Mexico and North America but the rapid spread of the virus in Australia has seen some new cases among people who travelled there.

A total of 1,307 cases had been confirmed in Australia Friday, as the World Health Organisation said the world was in the "early days of its first influenza pandemic in the 21st century."

All of the infections in New Zealand have been among people who had travelled overseas or their close contacts and so far there had been no evidence it had spread in the wider community, officials said.

The country remained in the "keep it out and stamp it out" phase, they added.

New Zealand was one of the first countries outside Mexico to report swine flu infections, with most of the initial cases occurring among a school group that had travelled to the American nation.

The latest WHO figures show that the number of reported global infections has reached 28,774 in 74 countries, including 144 deaths.