A 1.5-kilometre lockdown zone was established around a farm after the virus was discovered there on Wednesday.
Today, testing by a NSW bio-security team confirmed that a second farm, located within the locked down area, had also identified cases of the disease.
The CSIRO’s Australian Centre for Disease Preparedness confirmed a positive result for the H7N8 strain of high pathogenicity avian influenza (HPAI).
Bird flu, or avian influenza, is a highly contagious viral disease primarily affecting birds and has a high mortality rate.
This virus detected today is the same strain found on the other nearby farm.
It is different to the strain of virus recently identified in outbreaks in Victoria, and other global outbreaks.
“The biosecurity plan is working and because teams responded rapidly, we have been able to quickly survey, test and detect another site, that had been locked down on Wednesday 19 June,” NSW Minister of Agriculture Tara Moriarty said.
“The depopulation process is being carried out under the supervision of biosecurity officers, consistent with national policy,” a statement from the minister said.
Around 87,000 birds will be destroyed.
Eggs and poultry meat are safe to eat provided they are handled and cooked according to safe food handling practices.
The public were encouraged to report sick birds to authorities, including wild birds.