Breaking: Third H5N1 bird flu case confirmed as virus found in South Australia

A third confirmed case of the deadly H5 bird flu has been found in a migratory bird on Australia's southern coast.

Warning: This story contains an image of a dead animal some readers may find distressing.

South Australian Premier Peter Malinauskas said the state recorded the avian influenza in a giant petrel found at Knights Beach on the Fleurieu Peninsula.

He said two sick birds came into the care of a local wildlife rescue group on June 14.

"Once that was drawn to the attention on June 19 to the relevant authorities in South Australia, we responded quickly and enabled and facilitated active testing of those birds for H5 bird flu," the premier said.

"This afternoon we received those results and they confirmed that one of those birds was negative and one them was positive."

Mr Malinauskas said the volunteers who handled the birds would be given anti-viral medication if necessary.

He urged people who see unwell or dead birdlife to "avoid, record and report."

"They can do that through our hotline 1800 675 888.

"It's also important to emphasise that this is a migratory bird, this is not a contamination or infection that has come from WA to SA."

Mr Malinauskas said two other sick birds found at Fowlers Bay yesterday had tested negative for the virus.

It comes after two birds were confirmed to have the disease near the town of Esperance in Western Australia.

Another suspected WA case

Meanwhile, WA authorities said an additional bird had tested positive for the virus, but will need to be confirmed by the CSIRO.

That bird was found 700 kilometres north-west of Esperance near the tourist town of Dunsborough.

Federal Agriculture Minister Julie Collins said she was in contact with both of her WA and SA counterparts about managing the cases.

"At this stage there is no evidence of any mass mortalities, there is also currently no evidence of infection in poultry or in our agricultural production system, and there continued to be a low risk to human health," she said.

Her WA counterpart, Jackie Jarvis, said there was no evidence the virus had spread to native birds or wildlife.

However samples had been taken from a dead porpoise found in the Esperance region at the weekend, and were being tested for the bird flu.

"We do not know how long the porpoise was dead for, and so I will urge caution, if those samples are OK to be tested, they will be tested," she said.

WA chief veterinary officer Michelle Roden said this particular strain of the bird flu meant it was unlikely to spread from mammal to mammal.

“Generally with mammals, the way that they get infected is actually consuming a bird, so usually it's animals that eat birds," she said.

More seabirds are expected to wash ashore in Western Australia as the coast is battered by a forecast low-pressure system this weekend.

"They are used to being out there in storms, but if they're not well to begin with, then that's when it's not good," said BirdLife WA's Christine Wilder.

She said people should take extreme caution around sick birds.