Hackers have posted a list of two hundred government email addresses to public site pastebin, along with 25 unconfirmed usernames and passwords.
Prolific hacking group TeamP0ison claimed credit for posting the information, which included addresses of Australian federal and state senators and departments.
The hacker, Hex00010, told iTnews' sister publication SC Magazine that it targeted Australian government accounts to "send a message to corrupt governments".
"In today's society, international governments are corrupted. I have targeted Aussies' servers due to the fact that statistically ... from a cyber attacks perspective, Australia is not hit that much compared to other national governments," Hex00010 said.
"We have attacked a third world country listing hundreds of government officials."
The hacker claimed to have the username and password combination of Julia Gillard's email account which they "took for my own keeping".
But the lists may be outdated. AusTrac told SC Magazine an official of the agency named in the documents left in 2009.
It also said the password linked to the official was incorrect.
Government agencies had not confirmed the validity of named usernames and passwords.
Australian departments listed on the breach included AusTrac, IP Australia, the Bureau of Meterology, NSW Police, local councils, and hundreds of senator email addresses including Treasure Wayne Swan.
Nine accounts for Britain's Ministry of Defence included usernames and passwords.
Also included were emails for Fiji Government ministers and one for the Auckland District Health Board.