It comes as the Department of Defence told a parliamentary inquiry there had been over 1200 actions under its internal whistleblowing system since its inception in 2014.

Department of Home Affairs boss Michael Pezzullo told an inquiry reviewing the impact of police and intelligence powers on press freedom that whistleblowers also had the opportunity to go to police.

He said he supported the media exposing illegal operations by defence forces or intelligence agencies, but Australia didn't do that.

"We don't run off-the-book programs that are not known to this parliament," Mr Pezzullo said.

He also stood by his previous comments that leakers should face the full force of the law.

"If that involves a term of imprisonment, so be it," Mr Pezzullo said.

Department of Defence associate secretary Rebecca Skinner told the committee her department had received over 1900 referrals under its Public Interest Disclosure Act, with over 1200 actioned.

Ms Skinner also said the leak of a proposal for Australia's cyber intelligence agency to be allowed to spy on Australians without a warrant was considered "an insider threat".

Australian Signals Directorate acting-director general John Frewen said the directorate had a "handful" of matters raised under the disclosure scheme in the past 18 months.

He said there had also been a dozen matters raised with the intelligence ombudsman, the Inspector-General of Intelligence and Security, in the past five years.

Mr Frewen said the news story on the proposal sought to undermine public confidence in Australia's intelligence agencies.

Both Mr Frewen and Defence representatives argued that simply revealing the proposal undermined the national interest.

The committee also heard Australian Federal Police treated unauthorised disclosures of classified commonwealth information as corruption.

Procedures around contacting Home Affairs Minister Peter Dutton's office before they executed search warrants had changed after they were "probed" by a parliamentary privileges committee.

The police had contacted the minister's office in the lead-up to raids over leaks relating to the au pairs matter.

But after they were put before the privileges committee, the AFP didn't contact the minister's office before raiding the ABC or the home of News Corp journalist Annika Smethurst.

The committee also heard from Home Affairs heads that they didn't know how many journalists were under warrant.

News Corp Australia group executive Campbell Reid later told the committee his blood "ran cold" when he heard that, because he'd assumed there would only be a handful.

"The answer seems to suggest otherwise," Mr Reid said.

Mr Reid also challenged the police's assertion that they didn't "raid" journalists homes, but "executed search warrants".

"If it looks like a raid and feels like a raid, then it's probably a raid," Mr Reid said.

Australian Associated Press