The Australian Bureau of Meteorology (BOM) has asserted that its systems are fully operational and reliable in response to a report by the ABC that the weather bureau had suffered from a large breach.
"It could take years and cost hundreds of millions of dollars to fix," a source told the national broadcaster.
The ABC said it was told that the source of the attack was China.
In response, the BOM was tight-lipped.
"The Bureau does not comment on security matters," it said. "Like all government agencies, we work closely with the Australian Government security agencies."
Late last week, the Australian government released a second exposure draft of legislation requiring telecommunications providers to increase network protection and provide greater oversight to government agencies to intervene for the purpose of protecting national security.
Under the proposed legislation, carriers and carriage service providers "must do their best" to protect their networks against unauthorised access, with the Bill also vesting an information-gathering power "to facilitate compliance monitoring and compliance investigation activity" with the secretary of the AGD; provides the attorney-general with the vague power to direct a CSP "to do or not do a specified thing"; and outlines enforcement mechanisms and remedies for non-compliance.
The government also decided to retain its Department of Finance-run secure interdepartmental network, Intra Government Communications Network (ICON), last week.
"At this time, a potential sale or lease would not represent value for money for the government," Minister for Finance Mathias Cormann said on Friday.
"The scoping study found that ICON provides significant value to the government as a strategic asset, and is highly valued by government agencies for its low-cost and high-volume bandwidth, which facilitate the provision of secure, cost-effective telecommunications services."
China is regularly accused of conducting cyber attacks against the nations of the Five Eyes alliance -- comprising the US, the UK, Canada, Australia, and New Zealand.
In June this year, China was initially blamed as the source of an attack on the US Office of Personnel Management, which saw the personal details of over 22 million current, former, and prospective federal employees stolen.
By September, the US director of national intelligence James Clapper was more circumspect when giving testimony to a US Senate committee. Clapper said the attribution for the attack on the Office of Personnel Management was "not simple", and that there were "differing degrees of confidence" across the intelligence community as to who is to blame.
NSA director Admiral Michael Rogers told the committee that China was more persistent in terms of volume of cyber attacks against the US, but Russia was more capable.
Earlier in September, the US and China had signed an agreement to prevent economic espionage from being conducted online between the two countries. However in October, cloud security company Crowdstrike said China was continuing to attempt to breach US companies.
"The very first intrusion conducted by China-affiliated actors after the joint Xi-Obama announcement at the White House took place the very next day -- Saturday, September 26. We detected and stopped the actors, so no exfiltration of customer data actually took place, but the very fact that these attempts occurred highlights the need to remain vigilant despite the newly minted cyber agreement," Crowdstrike co-founder and CTO Dmitri Alperovitch said.
According to Alperovitch, hacking attempts were continuing to persistently occur, with SQL injection being the preferred attack vector used.
In July this year, US presidental hopeful Hillary Clinton told her Democratic party supporters that China is "trying to hack into everything that doesn't move in America" and stealing government information.