A NEW South Wales woman has tested positive to swine flu in Australia's first confirmed case of the illness, Queensland's chief medical officer says.

The woman flew into Brisbane from Los Angeles on Thursday and tested "weak positive'' to the human swine influenza.

Queensland's chief health officer Dr Jeannette Young said the expert advice is that the woman, who was sick overseas, was no longer infectious at the time of boarding her flight to Australia.

But Dr Young said passengers who were sitting close to the woman on the flight and her family members were being contacted by authorities.

"Because we're taking every precaution, we will be contacting passengers from the same flight sitting close to the woman, and her close family, to check if they have had any illness and alert them to seek medical advice if they become unwell," Dr Young said.

"While advice from state and commonwealth experts is that other passengers are highly unlikely to become unwell because the woman was not infectious when she got on the flight, any other passenger on the flight with concerns can contact 13 HEALTH or visit their local GP."

The World Health Organisation (WHO) laboratory in Victoria confirmed the case was human swine flu influenza early this morning.

The woman began experiencing symptoms while in the United States on April 27 and arrived in Brisbane on flight QF16 on May 7.

She was screened and swabbed at the airport, given a mask and went to stay with her family, who live in Brisbane, while awaiting test results.

Hundreds of people have been tested for swine flu in Australia but the NSW woman is the first confirmed case.

Three Australians living in the United Kingdom have tested positive for swine flu.

Federal Health Minister Nicola Roxon is currently holding a press conference in Canberra on the swine flu situation.

Queensland Health is currently testing four other people for possible human swine flu influenza as part of its precautionary testing program.

Dr Young said personal hygiene remained vital.

"All Queenslanders can do their bit by following normal flu season hygiene procedures, such as regular hand washing, covering their nose and mouth if sneezing or coughing, and staying home if they are sick," Dr Young said.

The WHO said yesterday that 2500 people in 26 countries had tested positive for the influenza A (H1N1) virus.