The CSIRO says two native birds found dead on separate beaches in South Australia have tested positive for the H5 strain of bird flu.

It is the first time a case has been confirmed on a SA metropolitan beach.

The two additional cases were flagged yesterday as suspected cases.

A greater crested tern was found near Robe on South Australia's Limestone Coast, while another greater crested tern was found at a beach ramp near the Semaphore Surf Life Saving Club, north-west of Adelaide.

Acting Australian chief veterinary officer Sam Hamilton said there have now been 20 confirmed or presumed positive detections of H5 bird flu in Australia.

"All of these have been individual wild seabirds found in coastal locations," Dr Hamilton said in a statement.

"There remains no evidence of any mass mortality events and there are no detections in poultry or in our agricultural production system.

"The risk to human health remains low."

SA Environment Minister Emily Bourke said on Saturday the bird found in Robe was located 4 kilometres from the location where the first Australian seabird confirmed to have the H5 strain of bird flu was found.

"Unfortunately, we are finding that these two cases are in our local [bird] species,"Ms Bourke said.

Previous confirmed cases involved migratory birds from the sub-Antarctic region.

South Australia's first confirmed case was in a giant petrel found on the Fleurieu Peninsula on June 14.

As of today, there are seven confirmed cases in SA, 10 in WA, and two in NSW.

Queensland confirmed its first H5 bird flu case yesterday after a dead petrel was found on Moreton Island, east of Brisbane.

Before the two suspected cases were confirmed on Sunday, Premier Peter Malianauskas said the government's policy in response to the bird flu remains the same.

"We still don't have any evidence of it being anywhere near poultry facilities or the poultry industry, which of course is the biggest risk that we're keeping a close eye on,"Mr Malinauskas said.

The premier said despite there being evidence of the bird flu in the native Australian bird population, he had received advice it cannot be "automatically assumed that means a spread throughout the population."

"But that's nonetheless something we have to continue to monitor," the premier said.