Facebook accounts linked to Russia had a far greater reach than what was previously known, reaching nearly half the U.S. population.

Russia-linked Facebook accounts reached as many as 126 million users, according to prepared testimony from General Counsel Colin Stretch. Stretch's disclosure comes before a Congressional hearing on Russia's use of Facebook and other social media platforms during the election.

In prepared remarks, Stretch, said the company's "best guess" was that as many as 126 million people saw posts linked to Russia-backed accounts, though he attempted to downplay the significance of that number saying that it represented only a fraction of all News Feed posts.

Our best estimate is that approximately 126 million people may have been served one of their stories at some point during the two-year period. This equals about four-thousandths of one percent (0.004%) of content in News Feed, or approximately 1 out of 23,000 pieces of content.

The social network previously said Russia-bought ads reached about 10 million users. But it's now clear that "organic posts" linked to these accounts—that is non-paid posts published to individual accounts and pages—were even more influential than the ads for which Facebook had previously come under fire.

The latest disclosures show that Facebook's role in spreading misinformation linked to Russia was far greater than Facebook previously realized. CEO Mark Zuckerberg was sharply criticized for saying it was a "crazy idea" that his company could have played a role in influencing the election -- a statement for which he later apologized.

"Many of the ads and posts we've seen so far are deeply disturbing — seemingly intended to amplify societal divisions and pit groups of people against each other. They would be controversial even if they came from authentic accounts in the United States. But coming from foreign actors using fake accounts they are simply unacceptable," Stretch wrote in his testimony.

Stretch also shared new information on how Russian groups used photo-sharing service Instagram. Instagram deleted "roughly 170 accounts" that were responsible for at least 120,000 posts on the app. Previously, the company shared that "about $3,700" was spent on Instagram ads, totaling 5 percent of the ads it shared with Congress.

Stretch noted Facebook is working with other companies, including Google and Twitter, as part of its internal investigation.

Google is also expected to testify before Congress this week about how Russia-backed accounts leveraged its platform, including YouTube, to influence the election. Google so far has discovered nearly $5,000 in search and display ads, 18 YouTube channels, and "numerous" Gmail accounts tied to Russian actors, Recode reported Monday.

In a blog post, Google said it "will be launching several new initiatives to provide more transparency and enhance security," in the wake of its findings.

Twitter hasn't publicized its findings yet, though the company is also expected to testify this week.