A cyber attack on the Australian parliamentary computer network in 2011 may have given Chinese intelligence agencies access to lawmakers' private emails for an entire year, the Australian Financial Review reported on Monday.
The newspaper, citing government and security sources, said new information showed the attack had been more extensive than previously thought and "effectively gave them control of" the entire system.
"It was like an open-cut mine. They had access to everything," a source told the newspaper.
Australian officials, like those in the United States and other Western nations, have made cyber security a priority following a growing number of attacks.
The parliamentary computer network is a non-classified internal system used by federal lawmakers, their staff and advisers for private communications and discussions of strategy.
While inside the system, hackers would have had access to emails, contact databases and any other documents stored on the network, the report said.
The access would have allowed China to gain a sophisticated understanding of the political, professional and social links of the Australian leadership and could have included sensitive discussions between lawmakers and their staff.
Domestic media initially reported on the breach in 2011, although it was believed at the time that Chinese agents had only accessed the system for about a month.
Last year, the Australian Broadcasting Corporation reported that Chinese hackers had stolen the blueprints of a new multi-million-dollar Australian spy headquarters, as well as confidential information from the Department of Foreign Affairs and Trade.
Prime Minister Tony Abbott's government upheld a ban on China's Huawei Technologies Co Ltd from bidding for work on the country's $38 billion National Broadband Network (NBN) when it came to power last year, citing cyber security concerns.