Australia's major political parties have been targeted during a cyber attack by a foreign government on the Australian Parliament's servers.
But Prime Minister Scott Morrison said investigations into the recent hack were yet to find any evidence of electoral interference.
He confirmed earlier reports, revealed by the ABC, that the nation's cyber security agencies believed a foreign government was behind the attacks.
"Our cyber experts believe that a sophisticated state actor is responsible for this malicious activity," Mr Morrison told Parliament.
"Let me be clear, there is no evidence of any electoral interference.
"We have put in place a number of measures to ensure the integrity of our electoral system."
The impact to political parties was uncovered during an investigation of a breach of Parliament House's computer servers on February 8.
A spokesman for the Liberal Party said it was "working closely with security agencies on this matter".
The nation's chief cyber security adviser, Alistair MacGibbon, the head of the Australian Cyber Security Centre, said it was too early to tell what information the hackers had accessed.
"We know that this state actor has been interacting with those networks," he said.
"These are very early days and a decision was made, I believe rightly in terms of risk management, to go publicly with this issue before we knew the full extent."
Politicians and their staff lost access to their emails as security agencies reset passwords when the breach was detected.
Ministers and their offices were not affected in the suspected hack because they operate on different computer servers.
Mr MacGibbon said while the hacker's identity remained unknown, the list of suspects was small.
"The sophistication of their methodology to operate in those systems gives us the confidence to say it is a state actor," he said.
"There are a limited number of countries but we have low confidence at being able to publicly state who we think it is."
China eyed as possible source
Security agencies immediately starting looking into whether China was behind the attack, but the Prime Minister refused to be drawn on the location of the hackers.
Opposition Leader Bill Shorten said Labor and the Coalition had a "joint obligation" to protect Australia's democracy and national security.
He said the attack on Australia showed the country was not immune from attacks like those targeting parliaments and politicians around the globe.
"We cannot be complacent and, as this most recent activity reported by the Prime Minister indicates, we are not exempt or immune," Mr Shorten said.
"As the Prime Minister has indicated, government institutions, such as our electoral commissions, are largely well protected, but our party political structures perhaps are more vulnerable."
A Labor spokeswoman said the party wasn't making a statement beyond what Mr Shorten had said in Parliament.
In the wake of the breach, cyber security experts warned an attack on a foreign parliament would be the "crown jewels" for state-sanctioned hackers.