"They should go to jail for that."

It's hardly surprising the tsar of Australia's omni-security department would take such a dim view about leaks of classified information to journalists, and the fate that awaits public servants distributing the nation's secrets to the media.

But it's a sobering thought.

Home Affairs secretary Mike Pezzullo sat within the wood panelled walls of Federal Parliament's committee rooms on Wednesday, before an inquiry into the balance between press freedom and national security.

The contempt he holds for the individual who gave News Corp journalist Annika Smethurst a classified briefing discussing changes to the powers of the nation's foreign listening post, the Australian Signals Directorate, was palpable.

"Secondly, it was designed to play into a Canberra game about which agency is asking other agencies to expand its powers and remits," he said.

Federal Police raided News Corp journalist Annika Smethurst's house following a story she wrote a year ago. ( ABC News )

Mr Pezzullo's comments can be viewed as a stern warning to staff in his own department, and elsewhere in the public service, prompting an admonishment from the federal Opposition.

"He doesn't seem to appreciate the chilling effect which many, many witnesses spoke of, the intimidatory effect of these raids occurring, or indeed the intimidatory effect of him speaking in the way in which he did at the hearing yesterday," Shadow Attorney-General Mark Dreyfus said.

Senior national security sources suggest putting a journalist in the dock would be a shockingly bad public relations exercise. And you can bet it would be headline news, as the media looks out for its own.

"I think most Australians would say you would give as much leeway as possible to a journalist, because freedom of the press is one of the foundations of our democracy," Liberal Senator Eric Abetz said on Wednesday.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 24 seconds 24 s AFP Deputy Commissioner Neil Gaughan on the News Corp leak, suggesting it is a senior bureaucrat

Raids by the Australian Federal Police on Ms Smethurst's Canberra home and on the ABC's Sydney headquarters, on separate stories based on leaked classified information, are likely to have two consequences on media attitude.

There's no doubt it will prompt a concern about the criminalisation of journalism and the fear of sanction; but it could also foster an enraged response from the media, emboldened by the state crackdown on the exercise of the free press and a hope it can win over the general population in any ensuing PR war with the Government.

For whistleblowers, however, it's different.

While that battle plays out between the media and the Government, the conduits between the fourth estate and the nation's secrets would be quaking in their collective boots.

Even though they'd be backed by journalists keen to hear what they have to say, or receive whatever information they possess, whistleblowers would face a government machine unwilling and unable to absolve them of criminal responsibility for revealing allegations and evidence of misconduct, malfeasance and mismanagement.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 17 seconds 17 s AFP won't rule out charging journalist Annika Smethurst

Only the most altruistic and fearless public servants wanting to blow the whistle on the Government would do so.

And that's where the concern about the "chilling" effect the raids and police investigations, coupled with Mr Pezzullo's edict, flows from.

The Home Affairs boss would no doubt differentiate his comments to the committee with how he would react to other leaks, considering his further comments that Smethurst's story was entirely wrong and misconstrued the briefing document she based her reporting on.

He quipped "poor journalism" wasn't being investigated.

Regardless, we must remember there are two police raids that prompted this parliamentary inquiry.

No one has suggested the 2017 series of stories, known as the Afghan Files, by the ABC's Dan Oakes and Sam Clark was flawed.

Yet an investigation into the leak was still launched, and the public broadcaster's offices raided in search of evidence to find the culprit.