Australia's national cybersecurity chief says authorities are working to resolve a breach involving a major hospital and aged-care network.

St Vincent's Health Australia, which operates public hospitals in inner-city Sydney and Melbourne, is trying to work out what data has been stolen after it discovered a hack on Tuesday.

The breach is the latest in a series of hacks to hit large organisations, which have included damaging cyberattacks on telco Optus, private health insurer Medibank and port operator DP World.

National Cyber Security Coordinator Darren Goldie said government agencies were working to "address impacts" from the St Vincent's incident.

The breach had not appeared to affect the ability of the health provider to deliver services to patients, residents and the community, he said.

"Work to resolve this matter is ongoing," he said on social media platform X.

Prime Minister Anthony Albanese told reporters he was seeking a briefing on the cyberattack, details of which were revealed publicly on Friday.

St Vincent's, a non-profit organisation that also operates 10 private hospitals in NSW, Victoria and Queensland, said it "immediately took steps to contain the incident".

That included calling in external security experts and notifying relevant state and federal agencies after late on Thursday discovering cyber criminals had "removed" some data from its systems.

The organisation said it was working to determine what data had been accessed and stolen.

St Vincent's employs nearly 30,000 people across its various sites, including 26 aged-care facilities.