The Defence Department is cracking down on extremism within its ranks.

Public servants in the Defence Department are now banned from associating with extremist political groups, even in their spare time.

Changes mean the Australian Public Service Code of Conduct will now apply to private political activities.

In fact, department employees will be expected to dob-in any colleagues they think may be harbouring extreme ideologies.

Failure to report known associations of colleagues is now punishable under the Code of Conduct.

Staff have been warned that anyone seen to back supremacist views or in possession of offensive or belittling material will be in trouble.

An “extremism checklist” has been given to managers in the department that includes tips for spotting signs that staff might be flirting with extreme standpoints.

“Early detection and intervention can reduce the risk to defence and can protect defence personnel,” managers were advised.

“Indicators that a defence member is associating with a group of concern could include possession or display of literature associated with such groups, related ideology, doctrine, emblems, or changes in behaviour.”

The new rules for civilians come from a joint directive signed by Defence boss Dennis Richardson and the chief of the Defence Force, Air Chief Marshal Mark Binskin.

It warns that public servants should not “associate with, join or remain a member of groups or associations who engage in unlawful activities or engage, promote or espouse behaviours that are inconsistent with defence values”.

The department says being a part of such groups poses a clear security and reputational risk.