By Stephanie Borys for ABC
Australia's security agencies are investigating a cyber breach of the Federal Parliament's computer network that the ABC understands is likely the result of a foreign government attack.
The agencies are looking into whether China is behind the incident.
In a statement, Federal Parliament's presiding officers said authorities were yet to detect any evidence data had been stolen in the breach.
One source said the response to the attack had been swift but the hackers were "sophisticated this time around".
Computer passwords have been reset as a precaution as the investigations continue.
"We have no evidence that this is an attempt to influence the outcome of parliamentary processes or to disrupt or influence electoral or political processes," the Parliament's presiding officers said in a statement.
"Accurate attribution of a cyber incident takes time and investigations are being undertaken in conjunction with the relevant security agencies."
The Australian Signals Directorate (ASD) is working to secure the network and says action was taken as soon as the breach was detected.
"The necessary steps are being taken to mitigate the compromise and minimise any harm," ASD said in a statement.
A cyber security expert warned about the seriousness of the breach.
"If you look at what goes on in Parliament House, you've got politicians, you've got staffers, you've got government departments that are moving in and out of the organisation and a lot of that is through electronic means," adjunct professor Nigel Phair, from the University of Canberra, said.
"If I was a nation state, or dare I say any hacker looking for state secrets, this is the crown jewels."
Hackers caught in early stages, ABC told
Sources have told the ABC that the hackers were caught in the early stages of gaining access to the computer network.
The incident has been compared to a robber breaking into a house, whereby authorities know the front door has been broken but are yet to find out if anything else has been taken, or if there is another way to break in.
The attack does not affect the computer systems of government ministers and their staff, however it does affect government backbenchers, the Opposition and crossbenchers.
Labor politicians and staff said access to their emails had been intermittent since the attack.
Opposition Leader Bill Shorten said he was satisfied with the response so far.
"I've had some briefings on it. I'm satisfied from what I've heard initially that our security agencies and the president [of the Senate] and the Speaker [of the House] have moved in the right way to make sure that our parliamentary networks are secure," he said.
Mr Shorten described the breach as a "wake up call", saying while Parliament had the resources to respond to a cyber attack, many small and medium-sized businesses did not.
"They don't have the budget of the Parliament of Australia. If I'm prime minister I'm going to invest a lot more in the cyber security of our small and medium sized enterprises."