The statement said some of the organisation's digital and technology systems were inaccessible due to the incident.
Nine News said the impact due to ransomware and was much wider. The broadcaster reported that all operational systems, including internal staff email and booking of patient operations, forcing staff to use pen and paper instead.
It also said that the Wesley and St Andrews War Memorial Hospitals in Brisbane had their systems taken down.
According to its site, "UnitingCare also provides aged care, disability supports, health care and crisis response in Queensland through Blue Care, Lifeline, The Wesley Hospital, St Andrew’s War Memorial Hospital, Buderim Private Hospital and St Stephen’s Hospital. And we provide community, aged care, disability and mental health support in the Northern Territory through ARRCS."
The organisation's statement said: "As soon as we became aware of the incident, we engaged the support of lead external technical and forensic advisers. We also notified the Australian Cyber Security Centre of the incident and are continuing to work with them to investigate the incident.
"Where necessary, manual back-up processes are now in place to ensure continuity of most services.
"Where manual processes cannot be implemented, services are being redirected or rescheduled accordingly.
"Due to the recency [sic] of the incident, it is not possible to provide a resolution timeframe at this stage, however our Digital and Technology team are working to resolve this issue as swiftly as possible."
Last year, two prominent Australian healthcare providers were hit by ransomware. Regis was hit by the Windows Maze ransomware in August while Anglicare Sydney was hit by unspecified ransomware in September.
The last data breach report from the Office of the Australian Information Commissioner showed that health service providers were at the very top when it came to the number of notifications.
Commenting on the incident, Rick McElroy, principal cyber security strategist, VMware Security Business Unit, said: "Ransomware-as-a-service has risen in popularity, providing cyber criminals with the necessary tools to carry out these types of attacks.
"This has created the opportunity for millions to easily target healthcare organisations. Compounding these risks is the adage of affiliate programs for ransomware groups, providing new and unique ways for malware operators to have others deploy their payloads for a cut of the eventual profits.
"We’re also seeing a lot of secondary extortion, in which cyber criminals look to profit twice from an attack, forcing organisations to not only pay to decrypt data, but also to prevent sensitive data from being sold or released publicly."
McElroy said it was necessary for healthcare organisations to understand the evolving threat landscape but that was just half the battle.
"There are three things to keep in mind to help stay one step ahead of attackers: next-generation anti-virus, end-point protection and IT tracking tools.
"Endpoint protection platforms should incorporate defences for each phase of ransomware attacks: the delivery, propagation, and encryption stages. It’s important for organisations to ensure they can easily provision access to new users while maintaining data privacy, compliance, and security practices.”
VeroGuard chairman and co-chief executive H. Daniel Elbaum said: "Medical institutions have been under pressure for many years to integrate clinical, hospital, allied health, insurance, state and federal systems together, and now, new technologies such as artificial intelligence, big data, analytics and virtual reality will add further complexity and greater vulnerabilities to already stressed systems.
"Like most industries the focus on cyber detection and remediation in healthcare has been, and will continue to be, simply inadequate. With the average time to identify a breach increasing to more than 207 days in 2020, most of the damage is done before a breach is uncovered. Staff education is important however humans remain susceptible to attacks particularly in high pressure environments such as hospitals."