An Indian techie has allegedly hacked the Royal Australian Air Force website and posted a message asking Prime Minister Kevin Rudd's Government to take all steps to stop racist attacks against Indian students.

Australia's Department of Defence has said the website was hacked between Monday and Tuesday but did not elaborate on the issue, 'The Age' newspaper reported on Thursday.

Citing its sources, the paper said the message read, "This site has been hacked by Atul Dwivedi. This is a warning message to the Australian government. Immediately take all measures to stop racist attacks against Indian students in Australia or else I will pawn all your cyber properties like this one."

The department kept the entire RAAF website offline and replaced it with a page explaining that there had been "technical difficulties". The site has now been restored.

A Defence spokeswoman said the RAAF website was not used to conduct official air force business and no sensitive information had been stolen. The internal "intranet" systems were secure and had not been compromised.

Twenty Indian students have been attacked in Australia since last month. Australia hosts over 5 lakh international students, including 97,000 Indians.

"No sensitive information was compromised as the air force internet website is hosted on an external server and, as such, does not hold any sensitive information," the spokeswoman said, adding "Further, the server is not connected to any operational Defence systems."

Defence Security Authority is conducting an investigation into the incident.

The department did not comment on the technical aspects or what action would be taken against the hacker, due to the "active investigation".