A dramatic public confrontation between the Immigration Department and a Sydney-based political activist over her Facebook page has resulted in accusations that mass surveillance is being used to keep tabs on political dissent.
Other large government departments including Centrelink, Defence and Social Services have all conducted mass monitoring of social media activity.
Centrelink's parent agency, the Department of Human Services, even has its own software, which was developed by the CSIRO. A social media team of 10 public servants operates the software.
Immigration experimented several years ago with powerful software called Radian 6, which can provide surveillance across a range of social web platforms, but decided not to adopt it.
The department's key research contractor has told Fairfax that the monitoring currently undertaken for Immigration was about ''taking the temperature of society'' and that no reputable research company would help government departments compile ''hit lists'' of political opponents.
But pro-asylum seeker campaigner Vanessa Powell said she was intimidated when the department tweeted her about an ''offensive remark'' it said should be removed from her Facebook thread immediately or the government would ''consider our options further''.
''I felt quite intimidated and threatened as well because I didn't know what action they were referring to when they said, 'We will consider our options further','' Ms Powell told Fairfax.
When she identified the post in question - a comment using ''foul language'' a friend had made about a photograph of a protest at a Sydney detention centre - she removed it.
''I was shocked that they were actively monitoring my account because it's just my personal page,'' the activist said.
''They have no right to be spying on members of the public.''
The secretive department refused to say how it became aware of the material on Ms Powell's Facebook account.
The department said it had no problem with ''discourse'' on politics or policies; it confronted Ms Powell over an ''offensive'' remark about one of its public servants.
Immigration said it would be ''inappropriate'' to disclose publicly how it became aware of Ms Powell's post but pointed out that the material was open to public viewing.
Written questions from Fairfax to Immigration about its social media monitoring were referred to the office of Immigration Minister Scott Morrison, which did not respond.