The tip came from USA law enforcement on Sunday night, Nathaniel Gleicher, Facebook's head of cybersecurity policy, wrote in the post. The blocked Facebook pages reportedly communicated mainly in French and Russian although the majority of accounts on Instagram were English-speaking.
A handful of Twitter accounts, some of them with more than 10,000 followers, told the citizenry to vote Wednesday, not Tuesday, in a tactic to give blatant false information.
Nearly all of the Facebook Pages associated with the blocked accounts appeared to be in French or Russian.
Gleicher said the company will provide an update once it learns more, 'including whether these accounts are linked to the Russia-based Internet Research Agency or other foreign entities'.More news: Khashoggi's body was 'dissolved' after murder: Advisor to Turkish president
This year's contest has been portrayed as crucial by both Republicans and Democrats because both chambers of Congress, and the accompanying ability to pass or reject President Donald Trump's agenda, are up for grabs.
The company announced its actions earlier in its investigation than typical "given that we are only one day away from important elections in the USA", he added.
Facebook's purge is part of countermeasures to prevent abuses like those used by Russian groups two years ago to sway public opinion ahead of the 2016 US presidential election.
They were widely criticized following the 2016 presidential election for allowing themselves to be exploited by foreign influence campaigns.
An internal investigation into the Iranian accounts found that more than 1 million Facebook users had followed at least one of the fraudulent pages, while about 25,000 users joined at least one of these politically oriented groups, according to a company statement.