CEO Mark Zuckerberg said Thursday that Facebook will continue to be a platform that will carry political speech some users may find objectionable, framing his argument as a matter of free expression prevailing over censorship.

"Whether you like Facebook or not, we have to recognize what's at stake and take a stand for voice and expression at this critical moment," Zuckerberg told an audience at Georgetown University in Washington, D.C. "I believe in giving people a voice because at the end of the day, I believe in people."

In recent weeks, Democratic candidates Joe Biden and Sen. Elizabeth Warren have demanded that Facebook remove Donald Trump campaign ads that make false claims.

After Facebook refused to intervene saying that it's not a political gatekeeper, Warren paid for a fake political ad that claimed Zuckerberg and Facebook have endorsed President Trump. The ad states in the next sentence that it's not true.

"I don't think it's right for a private company to censor politicians or the news in a democracy," Zuckerberg said Thursday.

He argued that it should be for voters to decide on a candidate's truthfulness and whether that's important to them, and that the company's practices with respect to transparency and sources of political advertising are now more stringent than those of broadcast media.

Reuters reported in October 2018, citing sources, that Facebook executives briefly debated banning all political ads, which produce less than five per cent of the company's revenue.

The company rejected that idea because product managers were loath to leave advertising dollars on the table, and policy staffers argued that blocking political ads would favour incumbents and wealthy campaigners who can better afford television and print ads, the sources said.

'I certainly worry about an erosion of truth'

Zuckerberg said that even if such a decision were taken, it would be problematic to draw that line, as the company would never ban issue-driven speech from private individuals and organizations.

"While I certainly worry about an erosion of truth, I worry about living in a world where you can only post things that tech companies decide to be 100 per cent true," he said.

Some Facebook critics have pushed for the company to be regulated more like a broadcaster, with a more activist gatekeeper role to keep out divisive content.

Zuckerberg said the company has a number of indicators to determine whether content is harmful, and tries to stamp out that which might encourage or incite violence.

Facebook has come under fire ahead of the next vote, given it was a critical conduit in the lead-up to the 2016 U.S. presidential election for bogus accounts.

As documented in special counsel Robert Mueller's report on Russian interference in the election, as well as testimony from Facebook officials, hundreds of accounts were created by the Internet Research Agency (IRA), located in Saint Petersburg, Russia, and believed linked to the Kremlin. The tens of thousand of posts from the IRA and similar accounts located in other foreign countries sought to roil the American electorate and generally favoured Republicans, U.S. intelligence officials found.

As well, Zuckerberg was forced to apologize for data privacy flaws after the tech company Cambridge Analytica was found to have harvested the information of millions of users, in service of political operators in both the U.S. ahead of the election and the United Kingdom as it prepared to vote on whether to stay in the European Union.

He did not address the privacy issues in his speech but pointed out that the majority of the IRA posts would have been "permissible political discourse if voiced by Americans."

The key, Zuckerberg said, is to better identify fraudulent accounts or clusters of accounts. He said Facebook removes "billions" of fake accounts a year, mostly in a manner of minutes.

Admitting to "unfortunate enforcement mistakes" in the past, Zuckerberg promoted the company's planned independent oversight board for people to appeal Facebook content decisions.

In a Facebook blog post outlining the oversight board's planned role last month, the CEO said the board's decisions would be binding, "even if I or anyone at Facebook disagrees with it."

'New challenges' all the time

In addition to questions regarding partisan politics, Facebook has faced criticism for allowing autocrats to more easily spread propaganda, as well as over response times to take down posts and videos related to deadly acts of violence.

Zuckerberg said the company's artificial intelligence systems are getting better all the time at identifying content that falls within that definition, claiming that 99 per cent of potential terroristic content is flagged and removed before being seen by users.

He also said Facebook monitoring systems have helped alert first responders to people in potential danger from others or threatening self-harm.

"These are new challenges, and our responsibility is to build systems that can respond quickly," he said.

The challenges encompass dozens of countries and languages, but not China.

"We could never come to agreement on what it would take to operate there," he said.

In defending the company's open approach to political speech on its platforms, which include WhatsApp and Instagram, Zuckerberg also took a shot at the Chinese-owned TikTok, which has been accused of censoring content emanating from Hong Kong protesters.

"Is that the internet that we want?" he said.

Zuckerberg is scheduled to appear next week before the House's financial services committee, where he is expected to be questioned about Facebook's plans to launch a digital currency.