A potential parliament house hack is under investigation by Australia's lead agency for cybersecurity.
The department of parliamentary services (DPS) email network was shut down over the weekend due to an IT system issue.
Assistant Defence Minister Andrew Hastie said the fault was linked to an external provider, with the connection to government systems severed immediately as a precaution.
"The government acted quickly, and we have the best minds in the world working to ensure Australia remains the most secure place to operate online," he said in a statement on Sunday night.
The Australian Cyber Security Centre is in contact with DPS, providing support and continuing to monitor the situation.
Mr Hastie said the situation served as a "timely reminder" for Australians not to be complacent on cybersecurity.
"Cybersecurity is a team effort and a shared responsibility," he said.
"It is vital that Australian businesses and organisations are alert to this threat and take the necessary steps to ensure our digital sovereignty."
The parliament house concerns follow the , disrupting its live programming out of Sydney.
The Australian broadcaster was unable to air its Weekend Today and Sunday Sports programs on Sunday morning and later attributed the outage to an attack on its systems.
In a note to staff, Nine's director of people and culture Vanessa Morley directed all employees across the country to work from home until further notice.
"Our IT teams are working around the clock to fully restore our systems which have primarily affected our broadcast and corporate business units," she wrote.
"Publishing and radio systems continue to be operational."
Ms Morley said office workers would "experience disruption to the Nine IT network", although emails did not appear to be impacted.
Nine's National Rugby League coverage, 6pm news bulletins and Sunday evening coverage went ahead as planned as the company enacted contingency arrangements.
Shadow treasurer Jim Chalmers said the cyber-attack was worrying.
"These are very concerning reports," he said.
"What we're hearing about here is a serious, and sophisticated, targeted attack on a media organisation."
