Another passenger from the flight that sparked New Zealand's swine flu scare has been confirmed to have the virus, bringing the tally of World Health Organization lab confirmed cases to four.

Director of New Zealand Public Health Mark Jacobs said on Friday evening that another passenger from Air New Zealand flight NZ1 from Los Angles to Auckland -- which also carried the Rangitoto College pupils diagnosed with swine flu -- had been confirmed as having influenza A/H1N1.

The result was confirmed on Friday afternoon by the World Health Organization lab in Melbourne.

The passenger was being treated with Tamiflu and is in isolation at home.

As well as the four confirmed cases, New Zealand also has 12 probable cases, 116 suspected cases and 388 people in isolation.

The New Zealand government on Friday ordered a new flu-fighting drug and boosted its existing vaccine order as the number of suspected swine flu cases in New Zealand continues to climb.

New Zealand health officials do not plan to stop using the term "swine flu" despite the World Health Organization changing the official name to "influenza A/H1N1".

Health Minister Tony Ryall said at a press conference that it was important to use a term the public understood.

"I've got no intention of changing how I'm referring to it."

Jacobs said the Health Ministry would use the term the WHO asked it to in official communications. But he intended to use language recognized and understood by the wider community when he communicated with them.

Ryall said that the ministry had ordered 125,000 courses of another anti-viral agent, called Relenza, to be added to the government's flu-fighting stock file. It is taken as a puffer, rather than a capsule like Tamiflu.

He said the drug had been ordered as a precaution.

The government had also boosted its seasonal vaccine order by 23 percent to cater to increased demand.

The World Health Organization says it is particularly concerned about the impact of swine flu on the Southern Hemisphere as it enters the flu-prone winter season.