By Rachael Ward in Melbourne

Shoppers have been urged not to panic-buy eggs after a mounting bird flu outbreak prompted a supermarket giant to introduced limits on egg purchases.

The highly pathogenic H7N3 strain of bird flu has been detected on five egg farms in Victoria’s southwest with more than half a million chickens euthanised in an effort to stop the spread of the disease.

Coles customers in every state and territory, except Western Australia, can now only buy a maximum of two egg cartons.

Coles says the limit is temporary but has not revealed how long it is expected to last.

“We are working closely with all of our suppliers to ensure eggs remain available for our customers and we are providing support to the industry in responding to the Avian Flu cases in Victoria,” a Coles spokesperson said.

Woolworths and Aldi do not have limits on egg purchases and no other national stores have publicised limits.

Over the past seven weeks the virus has been detected on five farms linked to Farm Pride, Avgo, Surf Coast Eggs and another business.

The affected farms in Meredith, Lethbridge and Terang have been placed into lockdown with at least 580,000 birds destroyed.

Australian Chicken Meat Federation chief executive Mary Wu said all affected farms produced eggs and did not anticipate any discernible impact to farms that produced chicken meat.

Authorities are confident they can get on top of the outbreak quickly and consumers should be assured it is still safe to eat eggs, Agriculture Minister Murray Watt said.

“There’s no risk of contaminated eggs getting into the system, the supply system,” Senator Watt said on Monday

“It’s also important to remember that the strain of avian flu that we see in Victoria is not the particularly deadly strain that we have seen in other countries around the world, that’s the way we intend to keep it.”

Stressful events can cause feelings of worry and unease, especially where there are levels of uncertainty involved, but there are things you can do to take care of yourself.

Federal Health Minister Mark Butler said the chief medical officer had been regularly briefing him on the outbreak and stressed this variant did not cross over into humans.

Victorian minister Natalie Hutchins discouraged customers from panic-buying cartons, as some did with toilet paper during the height of the COVID-19 pandemic.

“They don’t need to stock up,” Ms Hutchins said.

“We are the third biggest supplier around the nation as a state and we’ll continue to work with our farmers to make sure that pipeline of product is protected as much as possible.”

Victorian Farmers Federation vice-president and egg farmer Danyel Cucinotta said the industry was ramping up containment efforts to ensure eggs remained available and advised customers to shop around at local retailers.

“Victorian egg farmers are working hard to contain the risk of any further biosecurity outbreak and maintain a supply of fresh and affordable eggs,” Ms Cucinotta said.

Avian influenza is a viral disease found across the globe that spreads between birds or when feed and equipment is moved between sites.

The United States has imposed restrictions on imports of Victorian eggs and poultry products.