Facebook says 126 million American users may have seen content uploaded by Russia-based personnel over the last two years.
The social networking site released the figures ahead of a Senate hearing.
Other sites to scheduled for the hearing are Twitter and Google.
They are expected to explain Russia’s impact on the popular sites.
Facebook revealed about 80,000 posts were produced before and after the 2016 presidential election.
But Russia has repeatedly denied allegations that it attempted to influence the last US presidential election, in which Donald Trump beat Hillary Clinton.
The 80,000 posts were published between June 2015 and August 2017.
Facebook said they were posted by a Russian company linked to the Kremlin.
“These actions run counter to Facebook’s mission of building community and everything we stand for,” wrote Facebook’s general counsel Colin Stretch, Reuters reports.
“And we are determined to do everything we can to address this new threat.”
