A third confirmed case of the deadly H5N1 bird flu has been found in a migratory bird on Australia's southern coast.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."Malinauskas said two other sick birds found at Fowlers Bay on Tuesday 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.Meanwhile, WA authorities also confirmed an additional bird has tested positive for the virus, but will need to be confirmed by the CSIRO.That bird was found 700 kilometres north-west of the original site near the tourist town of Dunsborough.Federal Agriculture Minister Julie Collins told parliament she was in contact with both of her WA and SA counterparts about managing the cases.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.- ABC