Australia’s largest poultry producer has locked down its Western Australian chicken breeder farms after a deadly strain of bird flu was detected in Australia for the first time.

Ingham Company made the announcement concerning its farm and grower network operations in Muchea, Gingin and Mogumber, north of Perth, after two migratory birds were found in Esperance carrying H5N1 avian influenza.

While the virus has not been detected on any commercial properties in Western Australia, the company has heightened its biosecurity measures to mitigate any potential risks.

Inghams has banned all non-essential access at its farms and processing centres across Western Australia.

The company is also seeking an order to allow free range poultry to be kept indoors from WA’s Chief Veterinary Officer.

“These measures are in addition to the already strict standard protocols observed at all times across Ingham’s operations,” a company spokesman said in a statement to ASX.

“Should this be enacted, an exemption order from the Australian Competition and Consumer Commission is in place to protect the continuation of free-range product supply and labelling.”

A second bird tested positive for bird flu as authorities determine whether the highly contagious pathogen has been established in Australia.

Agriculture Minister Julie Collins confirmed a northern giant petrel found in the same region of southern Western Australia where a brown skua bird tested positive for H5 on Saturday had also returned a positive result.

“I want to reiterate that this is two birds that have been found with the H5 bird flu in an isolated area of Western Australia,” she said.

“I also want to reiterate at this time there are no there is no evidence of any mass mortalities, particularly in our wildlife.”

Authorities are investigating whether bird flu had been “established in the wildlife or established in Australia”.

At least 16 cases of “dead or sickly” birds have been reported to the WA Department of Primary Industries and Regional Development over the weekend, following the shock announcement of a confirmed case of H5 bird flu found in a brown skua bird in southwestern WA on Saturday.

The highly pathogenic H5 bird flu was found in several wildlife species on a sub-Antarctic Australian territory, which prompted warnings from authorities that Australia must prepare for potential outbreaks.

In February, the disease was found in animals living on Heard Island, an extremely remote territory located more than 4000km southwest of Perth and 1700km north of Antarctica.

Avian influenza primarily affect birds but can infect mammals too - posing a threat to livestock industries.

Australia’s Chief Veterinary Officer Beth Cookson said on Saturday the virus had been circulating for a number of years in other parts of the globe and had impacted native populations.

“It’s almost inevitable, let’s say, that there will be spread in wild populations of birds and mammals,” she said.