LEIGH SALES, PRESENTER: It's almost like the plot of a thriller. An ordinary person buys a couple of old, locked filing cabinets, breaks them open and discovers they're full of top-secret papers.

But it is no spy novel, it's real life and as we just heard on the news, it's one of the biggest leaks of classified material in Australian history.

That has big implications for national security of course but this leak also demonstrates something else with serious ramifications for Australia's democracy, and that is how hard it's becoming for journalists to expose the secret behaviour of governments thanks to ever-tightening laws on the reporting of this kind of material.

Reporter Tom Iggulden is at Parliament House and he's going to look to elaborate on all of that for us shortly. But first, Tom Canberra insiders must be reeling from this security breach?

TOM IGGULDEN, POLITICAL REPORTER: Well of course Leigh, everyone here is asking themselves how something like this could even have happened and, predictably enough, the secretary of the Department of Prime Minister and Cabinet Martin Parkinson, it is of course that Departments job to make sure this information doesn't come into the public domain. He's launched an investigation.

But there are also those who also predictably I guess have already suggested that things need to go much further than that. Former Prime Minister Tony Abbott hit Sydney radio this afternoon. He's saying there have to be consequences for whoever it was, in that department that was responsible for this very very serious breach Leigh.

Now as we know, as you would know having worked here. We are used to seeing Cabinet leaks coming in dribs and drabs here and there, but this Leigh, is a veritable flood of information. A unique insight into the inner sanctum of Government and how it makes decisions about everything from welfare, through to national security, and everything in between.

But as you alluded to there, Leigh, in your introduction, there are questions also being asked here in Parliament about whether it might be harder for journalists to do these sorts of stories. And I'm talking here about tough new anti-spy laws that were introduced into the Parliament at the end of last year to do with tightening up foreign interference and espionage activity here in Australia.

Now, there are already suggestions from some that those laws could impact on how journalists are reporting exactly the sort of stories that the ABC has been revealing this week.

NEWS REPORTER: 23 days in an Egyptian cell.

PETER GRESTE'S FATHER: He is not a criminal.

PETER GRESTE, JOURNALIST: That was devastating. We were doing our jobs. We were working with as much integrity as we could muster. And then to find ourselves on terrorism charges because of that work was utterly astounding.

TOM IGGULDEN: Jailed for doing his job, former foreign correspondent Peter Greste knows only too well what it's like to be hauled before a judge for reporting the news.

PETER GRESTE: We thought that, you know, with the evidence on the table, that we'd walk free pretty quickly because it was quite clear to anyone who watched the trial that there was no evidence that we were doing anything other than our responsibilities as reporters.

TOM IGGULDEN: He spent 400 days in an Egyptian jail, found guilty, along with two colleagues, of falsifying their reports from the country, and damaging its international reputation.

NEWS REPORTER: Al Jazeera journalist Peter Greste is free.

TOM IGGULDEN: But while he is not suggesting that Australia's anti-spy legislation proposed in Canberra is anything like Egypt's draconian laws, he does think Malcolm Turnbull's Government's over-reached.

PETER GRESTE: What concerns me here is, that we're redefining again the scope again that journalists are able to operate in. Ruling out a lot of work that we would not only traditionally be expected to do but have a democratic responsibility to perform.

TOM IGGULDEN: Debate over the new laws comes just as the ABC has been revealing a leak of Cabinet documents of historic proportions.

Two filing cabinets full of extraordinary details about the inner most workings on the nation's most powerful institutions. It is certainly an embarrassment for the government agencies meant to keep such documents under lock and key and for ministers of all persuasions mentioned in the Cabinet Files.

But, say those who argue against the new laws, it is also exactly the kind of vital public interest journalism that would be threatened if the laws were to be passed in their current form.

PAUL MURPHY, MEDIA, ENTERTAINMENT AND ARTS ALLIANCE: From what I've seen, the documents in those filing cabinets were classified, secret classified documents.

Therefore, under this bill, they are defined as "inherently harmful information". So, the communicating of them, if any of those documents that were labelled "top-secret" would draw an aggravated, come under an aggravated offence, with a maximum penalty of 20 years for the journalist and, potentially, other people in the media organisation for communicating those documents.

TOM IGGULDEN: The union representing journalists says the laws would make it illegal to communicate a whole range of documents not covered by current legislation, or even reports of a conversation, or anything that could be considered inherently harmful to the national interest.

The laws do have protections for journalists who'll be in clear if they can argue they were engaged in fair and accurate public interest journalism and don't use the information they gather to produce false or distorted reporting.

But the union says such protections aren't filling it with confidence.

PAUL MURPHY: These terms are highly subjective. They're open to interpretation. And, particularly, at a time when the term "fake news" is thrown around so readily, they are very concerning and they are not strong protections at all.

TOM IGGULDEN: Legal minds are also perplexed at the proposed laws.

MORRY BAILES, PRESIDENT, LAW COUNCIL OF AUSTRALIA: A journalist could unwittingly come into possession of information or evidence from a foreign actor and be caught by the offence of secrecy under the current bill.

TOM IGGULDEN: The Law Council says the legislation's riddled with vague definitions that are inconsistent with existing national security laws.

MORRY BAILES: We ought not to let it impose unreasonably on our implied right to freedom of expression under the Australian Constitution, and our common law right to freedom of speech.

TOM IGGULDEN: But far from undermining democratic principles, the Government argues the whole reason for the tougher anti-spying laws is to protect our most cherished institutions.

MALCOLM TURNBULL: Given the extreme threat these activities pose to our national security, the offences carry very severe penalties.

TOM IGGULDEN: When the Prime Minister unveiled the laws in December, it was in the midst of mounting public concern about China's attempts to influence the political debate, growing evidence of its espionage activities, and increasingly dire warnings from intelligence agencies about the need to beef up the nation's defences.

Today, senior intelligence officers have further outlined the case for new laws to Parliament's powerful National Security and Intelligence Committee. They say the scale of the threat from espionage and foreign influence is unprecedented.

PETER VICKERY, AUSTRALIAN SECURITY INTELLIGENCE ORGANISATION: It is something that we are seeing that we haven't seen before in terms of the volume in the scale that is occurring.

PARLIAMENTARY COMMITTEE: Including the Cold War?

PETER VICKERY: Beg your pardon?

PARLIAMENTARY COMMITTEE: Including the Cold War?

PETER VICKERY: Indeed, I mean the Cold War obviously was a busy time for a number of parts of the world but that was a different era, that was a different time.

TOM IGGULDEN: Labor accepts the overall need to update the legislation but Shadow Attorney-General Mark Dreyfus who is on the committee says it's important it's done without unintended consequences.

MARK DREYFUS: We don't want to criminalise the ordinary work of journalists, at the same time, we've got to pay attention to protecting Australia's national security. But there is a balance to be struck here and the impression I got very much listening to the submissions and reading the submissions that we've received is that the balance hasn't been struck in the right place.

TOM IGGULDEN: One journalist in particular is echoing that call.

PETER GRESTE: It seems kind of perverse to me that in trying to protect our freedoms we actually damage that freedom.

And I think that's what we're seeing happening here. If this goes ahead then I think we we're going to see a very serious limiting of the work that journalists do and the opportunity for civil servants to blow the whistle.