Sacha Baron Cohen has called social media companies "the greatest propaganda machine in history" for spreading hate, suggesting Facebook would have allowed Adolf Hitler to buy political adverts promoting the "final solution."
The actor and comedian accused Facebook, Google, YouTube, Twitter, and others, of putting business success above the safety of their users.
He called for them to be regulated, and classified as publishers, making them responsible for the fake news they spread, and forcing them to fact-check political adverts.
Speaking after accepting an award from the Anti-Defamation League (ADL) in New York, Baron Cohen called arguments used by Facebook founder Mark Zuckerberg, that he was protecting free speech, "absurd and ludicrous."
He accused the platforms, including Facebook, of allowing hateful content because it provoked a response and improved engagement.
Baron Cohen, who is Jewish, said: "Lies spread faster than truth. As one headline put it, just think what Goebbels could have done with Facebook.
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"If you pay them, Facebook will run any ‘political’ ad you want, even if it’s a lie. And they’ll even help you micro-target those lies to their users for maximum effect.
"Under this twisted logic, if Facebook were around in the 1930s, it would have allowed Hitler to post 30-second ads on his ‘solution’ to the ‘Jewish problem’."
Baron Cohen said demagogues around the world were using the platforms to appeal to people’s worst instincts, conspiracy theories were going mainstream, and scientific consensus was being dismissed.
He said: "Hate crimes are surging, as are murderous attacks on religious and ethnic minorities. What do all these dangerous trends have in common? I’m just a comedian and an actor, not a scholar, but one thing is pretty clear to me.
"All this hate and violence is being facilitated by a handful of internet companies that amount to the greatest propaganda machine in history."
A Facebook spokesman rejected the claims, saying: "Sacha Baron Cohen misrepresented Facebook’s policies. Hate speech is actually banned on our platform.
"We ban people who advocate for violence and we remove anyone who praises or supports it. Nobody – including politicians – can advocate or advertise hate, violence or mass murder on Facebook."
They also pointed to recent comments by Mr Zuckerberg about taking down hateful content.
In a speech Mr Zuckerberg said: "We take down content that could lead to real world violence. In countries at risk of conflict, that includes anything that could lead to imminent violence or genocide.
"And we know from history that dehumanising people is the first step towards inciting violence."
He added: "If you say immigrants are vermin, or all Muslims are terrorists, that makes others feel they can escalate and attack that group without consequences.
"So we don’t allow that. I take this incredibly seriously, and we work hard to get this off our platform."