AUSTRALIAN Facebook users are being left open to abuse, impersonation, and fake news with no way to defend themselves, experts warn, as the company is falling short of its promises to police the social media platform.

And governments need to introduce regulations, a dedicated ombudsman, and massive fines to stop the flood of fake news, they warn, as the multibillion-dollar company is not "financially motivated" to take action against the scourge.

The warning came as more Australian celebrities were swept up in scams advertised on Facebook this week, and after the US Declaration of Independence was incorrectly classified as hate speech on the site despite promises to hire thousands of additional content moderators to prevent the issues.

In the most recent high-profile scam on Facebook, TV newsreader Deborah Knight had her likeness used in a fake news story advertised on the platform, falsely claiming she'd left Channel 9 to promote face cream.

Newsreader Deborah Knight’s image was used to sell face cream without her permission.
Newsreader Deborah Knight’s image was used to sell face cream without her permission.

Three advertisements disguised as news stories appeared on Facebook for months despite reports and efforts to stop them.

Ms Knight's case followed other examples of fake endorsements on Facebook involving Eddie McGuire, Lisa Wilkinson, Shelley Craft, and Jessica Rowe.

A Facebook spokeswoman did not respond directly to the claims, but said the social network had made "recent improvements to combat impersonation," including facial recognition.

Media law expert Roger Blow, from Cove Legal, said he was "surprised" Facebook did not remove the fake reports quickly, as it could not afford more "high-profile arguments" following the Cambridge Analytica data scandal and increased scrutiny from politicians around the world.

But Mr Blow said the social network was still falling short of its obligations to remove defamatory comments, fake news articles, and fake accounts impersonating other users.

"Your average individual facing abuse, defamation, or insult is left relatively defenceless," he said.

"Facebook says it has lots of procedures, but most of the time those complaints, I find, get ignored. Even examples of clear abusive behaviour online - things to which no one could reasonably say 'no, that's fair game' - some of those still get knocked back."

Complaints rejected by Facebook are often too expensive for users to prosecute in civil courts, Mr Blow said, citing a case in which a client's son surrendered plans to sue the company over a fake account set up to bully him.

Another Facebook user, Sam Amjadali from Melbourne, told News Corp she had reported an Instagram account using her photo, name, and website more than five times, but Facebook repeatedly claimed the act did not breach its guidelines.

Technology adviser Kate Raynes-Goldie said the problem was that Facebook was not "financially motivated" to banish fake accounts or fake news, as the business relied on viral content.

"Basically, it's not in Facebook's interest to actually shut it down," she said. "It's not intentional - they didn't set out to create this problem - but their whole revenue model, that's how it works."

Mr Blow said only government regulation, financial punishment, or the introduction of an ombudsman would stop the flood of misinformation on Facebook, and provide "a fast-track solution" to individuals currently left with no redress.

RMIT media lecturer Gordon Farrer said Facebook should also go ahead with plans to introduce accredited fact-checking agencies to vet stories shared on its platform, but warned that users may ultimately have to play a role in shutting down false information.

"Facebook can't fix it," he said. "It's too easy to share stuff that is wrong. It's just too easy and it should be harder."