An outbreak of bird flu has been detected on a second farm in Sydney's north-west, with more than 86,000 chickens to be culled.
On Saturday the CSIRO's Australian Centre for Disease Preparedness (ACDP) confirmed the positive test result of the HPAI H7N8 strain of avian influenza in the Hawkesbury region.
The infected chicken meat farm is in the restricted biosecurity zone put in place after the virus was first found on Wednesday at an egg farm 1.5 kilometres away.
A total of 330,000 birds across the two farms will have to be destroyed.
The NSW Minister for Agriculture Tara Moriarty said the quick identification of the latest case was a sign the biosecurity measures, including proactive testing, were working.
She said that prior to Saturday, the chickens had no sign of infection and she was confident that all produce had been contained.
"That farm was already in a biosecurity zone ... I'm not concerned that product will have come out from that farm," Ms Moriarty said.
"But even if it has, chicken meat is safe for people to consume, so long as it's cooked in the usual way.
"We'll continue our tracing work for anything that has come out of either of these farms for the last couple of weeks, just to make sure that there hasn't been any spread."
She announced, however, the initial 1-2km containment area around the first confirmed site would be broadened out.
"We will be extending the biosecurity zone for another couple of kilometres to protect surrounding farms," she said.
"So the biosecurity rules that we have in place means that no product is coming in and out of that zone, no machinery is coming in and out of that zone.
"Everything has been cleaned and tested to make sure that it's safe before it moves ... people should be assured the industry is prepared for this."
'Playing out similarly to other outbreaks'
The HPAI H7N8 strain is not the same as the H5N1 strain that is causing concern globally.
It is also not connected to the Victorian outbreak of the of the H7N3 and H7N9 strains, which has impacted seven farms in the state.
NSW Premier Chris Minns said the public shouldn't be concerned about the outbreaks.
"It's certainly something that the government is focused on," Mr Minns said in a press conference on Sunday.
"I don't think that there's a need to unnecessarily worry people about this particular strain of bird flu in the community.
"The firm advice from health authorities is that there's no risk to human consumption. But we have to be careful."
NSW Acting Chief Veterinary Officer Emily Doyle was confident with the current control measures but acknowledged it was early days.
"It's not unsurprising that we've had a second positive so early in the outbreak. We're still learning a lot about the disease," Ms Doyle said.
"We have epidemiologists working really hard to try and understand what's happening with the disease.
"It's playing out similarly to other outbreaks. But it's it's very hard in those early stages to make big predictions about what's going to happen with a new version of a disease."
HPAI has been eradicated from NSW three times before, the most recent being in Young in 2013.