Russian Federation is accused of propaganda campaign in favour of Donald Trump in the 2016 presidential vote.
The action came after law enforcement authorities contacted Facebook to inform them of social media activity that they believe may be linked to foreign entities, Nathaniel Gleicher, the company's cybersecurity policy head, said in a release.
Facebook's investigation said it had identified around 30 Facebook and 85 Instagram accounts linked to the suspect behavior.
Almost all of the blocked Facebook pages appeared to be written in French or Russian, although the Instagram accounts were mostly in English, the company said, noting that some of the Instagram accounts focused on celebrities and political debate.
"Typically, we would be further along with our analysis before announcing anything publicly", he said.
The company said that they made the announcement despite being only in the initial stage of the investigation as the elections are only a day away and they want to inform their customers about the "action taken and the facts as we know them today".
Gleicher wrote that the accounts were immediately blocked after the company was notified Sunday evening of suspicious behavior and that the questionable accounts - potentially linked to foreign entities - are being investigated "in more detail".
Major online social platforms have been under intense pressure to avoid being used by "bad actors" out to sway outcomes by publishing misinformation and enraging voters.
Facebook also disclosed sophisticated attempts from Russian Federation to interfere with elections and promote political discord in the U.S.
It said it would provide an update once it knew more, including whether the accounts were linked to the Russia-based Internet Research Agency, widely recognised as a "troll factory" which ran fake ads on social media during the 2016 USA election.