The suspected first case of the deadly H5N1 bird flu on the Australian mainland is being investigated, after a migratory wild bird was found sick in southern Western Australia.

Initial testing at a WA laboratory returned a “suspected positive result for avian influenza”, the agriculture minister, Julie Collins, said.

Samples have been sent to CSIRO’s Australian Centre for Disease Preparedness for confirmation, with results expected on Saturday.

“There is no evidence of any mass mortality at this time. Nor is there any evidence of infection in poultry,” she said.

One sick bird was tested, and has since died, Collins said. A second unwell bird in a similar location had also been tested. The minister described them as “migratory wild birds”.

“If it is confirmed to be the H5 bird flu, this will be sobering, but not unexpected given the spread globally.”

“We certainly expected we couldn’t remain H5 free forever, as the only continent currently that is free of the H5 bird flu.”

She reminded people not to touch sick or dead birds, or other animals, and to report any sighting to the emergency animal disease hotline (1800 675 888) or to birdflu.gov.au.

Dr Carol Booth, a policy director with the Invasive Species Council, said while test results were necessary to confirm if it was the deadly H5N1 strain, the “detection is deeply concerning given the devastating impacts the virus is having on wildlife around the world”.

“We desperately hope this is not the realisation of our worst dreams. The recently reported mass deaths of elephant seals on Heard Island were a harbinger of the potential catastrophe for Australian wildlife if the virus has made it to mainland Australia.”

“If H5N1 is confirmed, the government’s own risk assessment predicts potentially catastrophic impacts on native birds, while the virus’s increasing ability to infect mammals raises the prospect of severe impacts on marine mammals and other wildlife.”

Booth said it was a “good thing” that Australian governments had spent the past two years preparing for the arrival of the deadly strain but a mainland detection would be “a critical test of Australia’s preparedness and response systems”.

“Even if this is a false alarm, it warns against any complacency. Australia needs to be ready at any time with clear response plans. It also highlights the urgency of mitigating other threats to potentially susceptible wildlife,” she said.

More to come.