As Australia braces for the arrival of the highly infectious H5 bird flu, egg shortages are affecting consumers already grappling with confusing labels.

Last month, major retailers, Coles and Woolworths, introduced a two-carton limit on egg purchases.

The move comes as the highly contagious H5N1 virus impacts bird populations around the globe. Experts expect H5N1 to reach Australia in the coming months and outbreaks in US diary cows and poultry workers is being monitored by the Centres for Disease Control and Prevention.

H6N1 is a subtype of the influenza A virus and causes severe disease, including death, in infected animals.

A Coles spokeswoman said that an outbreak of a different avian influenza, called H7, was currently impacting egg supplies nationally.

While egg shortages hit supermarkets, shoppers are also being impacted by confusing labelling, with the The Australian Competition and Consumer Commission changing the rules to allow eggs from hens kept indoors to be labelled free-range for up to 90 days during a H5N1 outbreak.

Eggs can only be labelled “free range”, in normal circumstances, if hens have regular outdoor access and are kept at no more than 10,000 per hectare.

Animals Australia lawyer Shatha Hamade says ACCC definitions for some terms around egg farming, has produced misrepresentations in packaging and marketing practices.

Animal welfare groups, including the RSPCA, say there are ambiguous and potentially misleading terms being used by brands to market their products, appeal to customers and potentially mislead Australians.

“Outdoor stocking densities of up to 10,000 birds per hectare are allowed,” RSPCA states.

“There is no requirement by law for free range farms to be assessed to ensure they adhering to the legal minimums.”

Coles did not respond to questions about how it ensures egg supply labels are accurate.

“We are working hard with existing and new egg suppliers to ensure eggs remain available for our customers,” the spokeswoman said.

“We expect availability to improve in the coming months.”

Woolworths did not respond to questions by the time this article was published.