Facebook has shut down more than 30 fake pages and accounts involved in what appeared to be a "coordinated" attempt to sway public opinion on political issues ahead of November midterm elections.
It said the "bad actor" accounts on the world's biggest social network and its photo-sharing site Instagram could not directly be tied to Russian actors, who US officials say used the platform to spread disinformation ahead of the 2016 presidential election in the United States.
A Russian propaganda arm tried to tamper in the 2016 US election by posting and buying ads on Facebook, according to the company and US intelligence agencies. Moscow has denied involvement.
But Facebook said on Tuesday that "some of the activity is consistent" with that of the Saint Petersburg-based Internet Research Agency (IRA) - the Russian troll farm that managed many false Facebook accounts used during the 2016 vote.
"We're shutting down 32 pages and accounts engaged in coordinated inauthentic behavior without saying that a specific group or country is responsible," Facebook said in a series of blog posts.
"We're still in the very early stages of our investigation and don't have all the facts - including who may be behind this," it added.
Facebook says it has uncovered sophisticated efforts to influence US politics on its platforms. Source: AAP
"But we are sharing what we know today given the connection between these bad actors and protests that are planned in Washington next week."
Facebook said it had briefed US law enforcement agencies, Congress and other tech companies about its findings.
The New York Times reported the company was working with the Federal Bureau of Investigation on the investigation.
The company said it was still in the early stages of its investigation and did not yet know who may be behind the influence campaign for 2018 elections that will determine whether or not the Republican Party keeps control of Congress.
But Facebook did say those behind the campaign had been "more careful to cover their tracks, adding: "We've found evidence of some connections between these accounts and IRA accounts we disabled last year (...) but there are differences too."
Some of the most-followed pages that were shut down included "Resisters" and "Aztlan Warriors."
The "Resisters" page enlisted support from real followers for an August protest in Washington against the far-right "Unite the Right" group.
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The Times, citing unnamed sources, reported that other "coordinated" activity revolved around #AbolishICE, a left-wing campaign against the Immigration and Customs Enforcement agency.
Facebook's chief operating officer Sheryl Sandberg said on a call with reporters the attempts to manipulate public opinion would likely become more sophisticated to evade Facebook’s scrutiny, calling it an “arms race.”
“This kind of behavior is not allowed on Facebook because we don’t want people or organizations creating networks of accounts to mislead others about who they are, or what they’re doing,” the company said in a blogpost.
The news comes just days after Facebook suffered the worst single-day evaporation of market value for any company, after missing revenue forecasts for the second quarter and offering soft growth projections.
Mark Zuckerberg's firm says the slowdown will come in part due to its new approach to privacy and security - one which helped experts uncover these so-called "bad actors."
Facebook CEO Mark Zuckerberg. Source: AP
"We face determined, well-funded adversaries who will never give up and are constantly changing tactics. It's an arms race and we need to constantly improve too," Facebook said.
"It's why we're investing heavily in more people and better technology to prevent bad actors misusing Facebook - as well as working much more closely with law enforcement and other tech companies to better understand the threats we face."
The company previously had said 126 million Americans may have seen Russian-backed political content on Facebook over a two-year period, and that 16 million may have been exposed to Russian information on Instagram.
The top Democrat on the US House of Representatives Intelligence Committee Adam Schiff urged Facebook to move against foreign groups trying to sway American voters and to warn legitimate users that such activity, as seen in 2016, is recurring this year.
“Today’s announcement from Facebook demonstrates what we’ve long feared: that malicious foreign actors bearing the hallmarks of previously-identified Russian influence campaigns continue to abuse and weaponize social media platforms to influence the U.S. electorate,” he said.
