Bird flu is detected at another Sydney farm with almost 100,000 animals to be euthanised

A highly infectious strain of avian influenza has been detected at a second Sydney farm in the Hawkesbury region, which will require authorities to euthanise 87,000 birds over the next seven weeks.

The case was confirmed by the NSW government on Saturday night, and was found 1.5km from the farm where the initial case of bird flu was detected last week.

Testing by the CSIRO's Australian Centre for Disease Preparedness (ACDP) confirmed the strain as High Pathogenic Avian Influenza (HPAI) H7N8 - the same strain which was detected at the nearby farm.

However the virus is not the same strain ravaging seven farms in Victoria, or the H5N1 virus which has infected more than 97 million birds and 118 dairy herds in the United States.

The second farm has been locked down since Wednesday, after the bird flu was detected at a large mixed barnyard and free-range poultry farm, affecting about 240,000 birds.

The outbreak is believed to be from a spillover event, like potential infection from a wild bird.

A 2km lockdown order was immediately implemented, which covered three other large commercial poultry farms, including the farm where Saturday's detection was confirmed.

The order restricted the movement of eggs, birds and machinery within the lockdown site,

NSW Agriculture Minister Tara Moriarty thanked the support and collaboration of the poultry industry, and said the virus didn't affect eggs and poultry meat, which was safe to eat as long as its handled and cooked according to safe food practices.

Supply chains have largely remained unaffected, however Coles has implemented a two dozen buying limit on all states and territories except for Western Australia.

People have been urged to report any sick and dead birds 'as a priority' through the Emergency Animal Disease Hotline on 1800 675 888.