Customers are being urged not to panic buy eggs after supermarket giant Coles banned individual customers in most of the country from purchasing more than two dozen at a time in response to a mounting bird flu outbreak.

Five eggs farms at Meredith, Lethbridge and Terang, in Victoria’s south-west, have been locked down and nearly 600,000 chickens euthanised to prevent further spread of disease after a highly pathogenic H7N3 strain of bird flu was detected over the past two months.