The Australian authorities say they are trying to hack the computer network of its parliament.
Lawmakers said there was "no evidence" that information was opened or stolen, but the passwords of politicians have been reset as a precaution.
Local cybersecurity experts have suggested that the hack probably comes from a foreign state.
Australian Prime Minister Scott Morrison said he did not intend to comment deeply on "the source or its nature".
He said there was "no suggestion" that government agencies or departments were the target. MPs and their staff use the parliamentary network to store e-mails, in addition to other data.
Previously, high lawmakers said there was no evidence that the hacking attempt was aimed at "disrupting or influencing electoral or political processes."
Opposition leader Bill Shorten, however, described the incident as a wake-up call & # 39 ;. It also led to comments from other legislators.
The Australian government has faced a number of cyber attacks in recent years, some of which have been attributed to local media to countries such as China.
In 2015 and 2016 there were high-profile attacks on the government's weather and statistics bureau. In 2011, senior Australian ministers had also violated their e-mail systems.
"It looks like another nation state is also behind this attack," said Fergus Hanson of the Australian Strategic Policy Institute, a think tank in Canberra.
"You would have access to a multitude of correspondence between politicians, staff members and people leading the Parliament House – lots of juicy information there."