Among the Facebook and Instagram accounts that were linked to Russian trolls ahead of the U.S. midterm elections this month, one on Instagram had more than 600,000 U.S. followers, Facebook said in a blog post on Tuesday.
A Russian troll farm was tied to more than 100 Facebook and Instagram accounts before they were blocked on the eve of the elections, Facebook said.
Based on a tip from the FBI on Nov. 4, the company identified and removed a total of 99 Instagram accounts, 36 Facebook accounts and 6 Facebook pages. About $4,500 in ad spending came from those pages, though none of the ads ran in the U.S., the company said.
The accounts may be connected to the Internet Research Agency, Facebook said. That's the same group responsible for Russian interference in the 2016 U.S. presidential election, according to a February indictment by Special Counsel Robert Mueller.
Facebook previously announced the removal of the accounts, but it had not disclosed the exact number of them, how long they operated or how many users they reached. Most were created after mid-2017, Facebook said.
The accounts posted content related to various social issues in the U.S. using hashtags such as #DonaldTrump, #MakeAmericaGreatAgain, #GayPride, #Feminism and #BlackPride.
Over the past year, Facebook has been plagued by a series of scandals involving its management and security of user data as well as its effort to curtail the spread of harmful content and misinformation on its service. The company has removed hundreds of accounts for sharing propaganda and spam and engaging in "coordinated inauthentic behavior," which includes misleading people using fake names.
"To stay ahead of this misuse, we need to continue to invest heavily in security, as well as our work with governments and other technology companies," Facebook said. "It will take the combined efforts of the public and private sectors to prevent foreign interference in elections."