Moscow has denied involvement.
"The most followed Facebook Pages were 'Aztlan Warriors, ' 'Black Elevation, ' 'Mindful Being, ' and 'Resisters, '" Facebook said.
"We face determined, well-funded adversaries who will never give up and are constantly changing tactics", Facebook said in a statement.
Evidence Facebook has is not strong enough to publicly attribute the pages to the IRA, and "it's possible that a separate actor could be copying their techniques", the company's chief security officer Alex Stamos said.
The first of the pages was created in March 2017.
The Times, citing unnamed sources, reported that other "coordinated" activity revolved around #AbolishICE, a left-wing campaign against the Immigration and Customs Enforcement agency.
The news release was written with as many euphemisms as Facebook's PR team could come up with, but the findings are still clear: Hidden groups are using Facebook's platform to run political influence campaigns behind false identities in advance of the upcoming U.S. midterm elections. A previous event a year ago in Charlottesville, South Carolina, led to violence by white supremacists.
Facebook said it worked with law enforcement to identify these bogus pages, and significantly increased the amount of resources it devotes to security to tamp down manipulation on the platform. It publicly said it had been unable to tie the accounts to Russian Federation, whose Internet Research Agency was at the center of an indictment earlier this year for interfering in the 2016 election, but company officials told Capitol Hill that Russian Federation was possibly involved, according to two officials briefed on the matter.
However, Senator Mark Warner, the top Democrat on the U.S. Senate Intelligence Committee, issued a statement tying the latest Facebook activity directly to Russian Federation. It's not clear what exactly would have happened if the pages weren't deleted beforehand, but we know what happened when Facebook didn't intervene with similar accounts during the lead up to the 2016 presidential election: the accounts fanned the flames of dissent, pushed Americans farther towards extreme views, and cemented those beliefs with confirmation bias.
"The goal of these operations is to sow discord, distrust, and division", said Senator Richard Burr, the committee's chairman.
Special counsel Robert Mueller's sprawling investigation into alleged collusion between the Trump campaign and Russian agents working with President Vladimir Putin has already indicted more than two dozen Russians, many with ties to the IRA, for their alleged disinformation campaigns. "The Russians want a weak America".
Last week, President Donald J. Trump tweeted that he is "very concerned that Russian Federation will be fighting very hard to have an impact on the upcoming Election [sic]", which was surprising as he had previously suggested Russian Federation had not interfered in the election. It's an arms race and we need to constantly improve too.
In October 2017, the social network admitted that Russia-backed content reached as many as 126 million Americans during the 2016 presidential election.
The social media company that it couldn't tie the activity to Russian Federation, which interfered on its platform around the 2016 presidential election. The ads were paid for in USA and Canadian dollars, the company added.
"It demonstrates again a huge vulnerability that we have where these people who claim to be somebody else can foment such conflict and dissension within our society", said Cornyn, the Senate's No. 2 Republican.
The company says the campaign included efforts to organize counterprotests on August 10 to 12 for the white nationalist Unite The Right 2 rally planned in Washington that weekend. Shares of Facebook were up about 1.5 per cent in Tuesday's midafternoon trading, part of a broader tech rebound.