Hackers are believed to have broken into computers owned by the Australian Prime Minister Julia Gillard and at least two senior ministers.
US intelligence agencies alerted the Australian government to the security breach, according to Sydney's Daily Telegraph.
Senior sources in the government have confirmed that the attacks took place over more than a month, beginning in February, the paper said.
It is believed that several thousand e-mails may have been accessed from the computers of at least 10 ministers.
The hacking attacks, which have not been confirmed or denied by Australian authorities, are said to have targeted the Australian Parliament House e-mail network.
According to local reports, the hackers are thought to have been working for Chinese intelligence agencies and appear to have been trying to access information about Australia's mining industry.
In February, security firm McAfee revealed that hackers from China had attacked the computer networks of global oil companies with the intention of stealing information.
McAfee said researchers identified the tools, techniques and network activities used in continuing attacks, dubbed Night Dragon, that date back to November 2009.