Coles is limiting the number of eggs customers can buy in-store because of the spread of bird flu in Victoria.

Coles supermarket is limiting the number of eggs customers can buy after bird flu was found at a fifth Victorian poultry farm.

Four infected properties near Meredith, between Ballarat and Geelong, are confirmed to have the high pathogenicity H7N3 strain of avian influenza, and an infection of the H7N9 strain has been detected near Terang, in the state's south-west.

Almost half a million chickens have been euthanized and quarantine zones have been set up, restricting the movement of birds and equipment.

Victoria is the third largest egg-producing state in Australia and the Victorian Farmers Federation said about one in 16 egg-laying chickens had been destroyed, reducing the state's supply by about 450,000 eggs a day.

Over the weekend, Coles announced it was introducing a temporary limit of two egg cartons per customer in all stores across the nation, except Western Australia.

'We are working closely with all of our suppliers to ensure eggs remain available for our customers,' a spokesperson said.

Eggs Australia is a member-owned not-for-profit company providing marketing, research and development services to Australian producers.

Managing director Rowan McMonnies said the outbreak was having a small disruption to supply but should not create a crisis across the board.

'Some of those farms were supplying to Coles so they've thought it was either necessary or responsible to go first and say we are going to limit supply,' Mr.

McMonnies told the ABC's Country Hour.

Mr.

McMonnies said the market was looking to find new sources to fill the gap left by the five producers.

'It's a difficult time, winter as well, the free-range birds tend to lay less because there's less sunlight so it's not perfect timing.

Federal Agriculture Minister Murray Watt said he was confident in the work of Victorian authorities to control the outbreak.

'It's now at a point where we do have bird flu in five different poultry farms across Victoria but frankly it would have been a lot more if the Victorian government, supported by the Commonwealth, hadn't moved as quickly as they had,' Mr.

Watt said.

He described the purchasing limit introduced by Coles as precautionary and urged shoppers to be respectful to staff.

Coles is limiting the number of eggs customers can buy in-store because of the spread of bird flu in Victoria.

Federal Health Minister Mark Butler told ABC News Breakfast he was getting regular briefings from the chief medical officer about avian flu in Australia.

'I know Murray Watt is watching that very clearly and I know Australian viewers will want to know that they're going to have access to enough eggs to keep having the hardy Australian breakfast so we are taking this seriously,' Mr.

Butler said.

Agriculture Victoria said serious forms of the disease can result in severe symptoms and sudden death in domestic poultry.

Restricted areas have been declared around the infected properties in Meredith, Lethbridge and Terang.

Permits are now required to move birds, eggs and poultry products, feed and equipment on or off the properties in these areas.

The Victorian Farmers Federation has urged poultry farmers, backyard flock, and bird owners to report any unexplained deaths.

'I can't stress more the importance of reporting any symptoms in birds to the Emergency Animal Disease Hotline on 1800 675 888, even in backyard hens,' said vice-president and egg farmer, Danyel Cucinotta.

'We're anticipating a flow-on impact to egg supplies in the coming week and are working as hard as possible to maintain availability.

' My advice is to shop around at your local grocer, market or small independent store to buy your eggs.

The strains detected at the five farms are not the same as the outbreak of H5N1 which is causing concern globally.

, when a child returning to Australia from overseas became unwell and tested positive for the H5N1 strain.

The case was not related to the outbreak on the poultry farms and the Victorian Department of Health has reassured the community that the chances of avian influenza spreading among humans in Australia is low.

'I'm making sure that our government particularly is across any implications that might have for human health,' Mr.

Butler said.

'It's a different type of avian or different strain of avian flu to the one we're seeing in some other countries that have led to a crossover.

' We acknowledge Aboriginal and Torres Strait Islander peoples as the First Australians and Traditional Custodians of the lands where we live, learn, and work.

This service may include material from Agence France-Presse (AFP), APTN, Reuters, AAP, CNN and the BBC World Service which is copyright and cannot be reproduced.