The number of confirmed cases of the H5N1 avian influenza strain in Australia has risen to 15 after a second east coast case was reported in the state of New South Wales (NSW) on Thursday.

Australia's Chief Veterinary Officer Beth Cookson said in a statement that testing by the Australian Center for Disease Preparedness detected the deadly H5N1 strain in a petrel found in the coastal NSW town of Hawks Nest, 160 km northeast of Sydney.

It brings the total number of confirmed H5N1 cases in Australia to 15, two in NSW, five in South Australia, and eight in Western Australia (WA), the last of which was reported on Wednesday.

Cookson said on Thursday that all 15 cases were wild seabirds found in coastal locations and 14 were migratory species.

"There remains no evidence of any mass mortality events and there are no detections in poultry or in our agricultural production system," she said. "The risk to human health remains low."

Prior to the first case being detected in WA in mid-June, the Australian mainland was the only continent free from the strain that has caused the deaths of millions of birds and other wildlife globally since 2020.