Facebook has said as many as 126 million American users may have seen content uploaded by Russia-based operatives over the past two years.
The social networking site said about 80,000 posts were produced before and after the 2016 presidential election.
Facebook released the figures ahead of a Senate hearing where it, together with Twitter and Google.
In a separate development on Monday, an investigation by independent counsel Robert Mueller into possible collusion between the Trump campaign and Russia produced its first charges against two former aides.
Facebook says some 80,000 posts were published between June 2015 and August 2017 and were seen by about 29 million Americans directly, according to a draft of prepared remarks seen by US media ahead of Tuesday's Senate judiciary committee hearing.
These posts, which Facebook says were created by a Kremlin-linked company, were amplified through likes, shares and comments and spread to tens of millions more people.