Australian federal government said on Friday the use of thermal imaging equipment to scan airline passengers is not a perfect system for detecting suspected cases of A/H1N1 flu, but it will help delay the spread of cases in Australia.

"It's not a perfect system," Health Minister Nicola Roxon told ABC Television, but added it would help delay the spread of any cases in Australia.

The scanners had been in use for about 36 hours and dozens of people had been detected.

Only five of those had been asked to provide a swab for testing. Three of those were asked to keep themselves in isolation at home.

"But at this stage none of those cases have moved to being even probable or likely cases of swine flu," Roxon said.

Roxon said it was always possible for the government to do more to help people prepare for an outbreak.

"We do have to get the balance right of providing information, but not alarming people," Roxon said.

People who wanted to stock up on long-life products could do so, but there was no indication of any need to at this stage, Roxon said.

Scanners have been rolled out across international airports in Sydney, Melbourne, Brisbane, the Gold Coast, Cairns, Adelaide, Perth and Darwin, to help authorities ramp up their defenses against the disease.

While there have been no confirmed cases of the virus in Australia yet, A/H1N1 flu was thought to have claimed the lives of 149 people in Mexico.