Australians have been warned the country is becoming a "police state" amid efforts to silence whistleblowers who act in the public interest.

Federal MP Andrew Wilkie was once a whistleblower. As an intelligence officer, he was concerned Australian troops were about to join the US invasion of Iraq in a hunt for weapons of mass destruction that did not exist.

History would prove him right, but his decision to speak up cost him dearly.

Critics have slammed government prosecutions of whistleblowers acting in the public interest. (A Current Affair)

"I lost a good job, I lost the income that went with it," he told A Current Affair .

"I instantly became unemployable in Canberra, my marriage failed, I lost a lot of friends for all sorts of reasons."

Another whistleblower who knows the cost of integrity is Jeff Morris, who first alerted the country to misconduct by financial planners at Commonwealth Bank.

MP Andrew Wilkie said Australia was becoming a "police state". (A Current Affair)

He said he knew he had to act after he realised fellow staff had lied to an elderly couple to "cover up" the half-a-million-dollar loss the couple had suffered.

His explosive revelations helped pave the way for the banking royal commission that shocked the nation.

Mr Morris not only lost his job, but also his marriage.

"In many ways it's the cause of some turmoil to me even today, thinking about what my wife and my kids had to go through as a result of the decision I made," he said.

Jeff Morris blew the whistle on misconduct by financial planners at Commonwealth Bank. (A Current Affair)

"I was offered any job I wanted if I wanted to stay, but the price of that would have been silence."

Now, more whistleblowers are facing even heavier penalties.

Four men are currently facing jail sentences of up to 160 years for the secrets they exposed.

One of those cases involves a former Australian spy known only as Witness K, and it could be held in secret hearings due to reasons of "national security".

Witness K's lawyer, Bernard Collaery, is being prosecuted too.

Four men are facing up to 160 years in jail for the secrets they exposed. (A Current Affair)

Witness K is before the courts over an incident that took place 15 years ago between Australia and East Timor.

Australian troops helped bring peace to East Timor after its independence, and Canberra was negotiating a treaty with its poorer neighbour over how to divide the oil and gas riches of the Timor Sea.

Australia's spy agency, ASIS, used the guise of an "aid project" to infiltrate East Timor's Palace of Government, and placed 200 covert listening devices in the Cabinet.

Witness K led that operation and eventually spoke up.

The case would end up at the International Court of Justice in The Hague and the treaty was eventually renegotiated with a fairer deal for East Timor.

Australian troops served in East Timor. (A Current Affair)

After the new treaty was signed, Witness K and Mr Collaery were both charged.

"The government is going after the whistleblower, who has done nothing more than trying to shine a light on misconduct, and the government's going after his lawyer, who's done nothing more than trying to represent his client," Mr Wilkie said.

"I can only assume the government is going after Witness K and Bernard Collaery now partly over vindictiveness, partly out of the desire to punish these two men.

"But perhaps even more alarming, as a deterrent to other insiders."

When ASIO first raided Mr Collaery's office, the government said it was for reasons of national security.

Lawyer Bernard Collaery is also being prosecuted by the government. (A Current Affair)

And national security orders now prevent him discussing any of the exact details of why he's been charged.

"If I comment, you might end up being prosecuted as well," he said.

Transparency International Australia CEO Serena Lillywhite said recent AFP raids targeting media outlets will scare future whistleblowers.

"It's too easy I think to say decisions are being made because it's in the national security (interest)," she said.

"What that is really doing is having quite a chilling effect."

Protesters demand extra protections for whistleblowers. (A Current Affair)

The federal government has enacted new laws offering greater protection for whistleblowers, but only in the private sector.

And Mr Morris says even those are sorely lacking.

"You have to make the logical conclusion there, which is that this government doesn't want whistleblowers coming forward," he said.

Mr Wilkie also offered a dire prognosis.