Lawmakers said there was "no evidence" that information had been accessed or stolen, but politicians' passwords have been reset as a precaution.

Local cyber-security experts have suggested the hack likely came from a foreign state.

Australian PM Scott Morrison said he didn't intend to comment in depth on "the source or nature of this".

He said there was "no suggestion" that government agencies or departments had been targeted. MPs and their staff use the parliament network to store emails, among other data.

Earlier, senior lawmakers said there was no evidence that the hacking attempt aimed to "disrupt or influence electoral or political processes".

However, opposition leader Bill Shorten described the incident as a "wake-up call". It also sparked commentary from other lawmakers.

The Australian government has faced a number of cyber-attacks in recent years, some of which have been attributed in local media to nations such as China.

In 2015 and 2016, there were high-profile attacks on the government's weather and statistics agencies. In 2011, senior Australian ministers also had their email systems breached.

"It looks like another nation state is behind this attack as well," said Fergus Hanson of the Australian Strategic Policy Institute, a Canberra-based think tank.

"You would be having access to swathes of correspondence between politicians, staffers and people who run Parliament House - lots of juicy information there."