The ads, he said, focused on divisive social and political issues, ranging from LGBT topics to immigration and gun rights.
Payment: Facebook says some of the ads were paid for in Russian currency, but it can't use that as an indicator of suspicious activity necessarily because "the overwhelming majority" of advertisers who pay in Russian currency aren't doing anything wrong.
Mark Warner, the U.S. Senator, this week claimed that he was saddened by Facebook for failing to give the newest data at the time of a briefing with staff of the Senate Intelligence Committee last week.
Numerous ads did not violate Facebook rules regarding banned content, but instead broke a policy barring accounts from hiding who is really running them, according to the social network. The company hasn't spoken publicly about how it was able to attribute the ads, but their findings have led them to conclude the fake accounts and ads were deployed by the IRA.
"Today we are delivering those ads to congressional investigators", Facebook vice president of global policy Joel Kaplan said in an online post. The companies have been asked to testify before the Senate on November 1.
Facebook would also increase requirements for authenticity and establish industry standards and best practices.More news: 5 arrested after explosives found in apartment building in 'chic' Paris neighborhood
To improve its ad monitoring system, Facebook just announced plans to hire 1,000 more ad reviewers.
Facebook handed over to Congress roughly 3,000 ads with links to Russian Federation on Monday.
A spokesperson for the company said its internal investigation is not finished. But Twitter - as it turned over information about those users as well as RT's ads - quickly drew the ire of lawmakers like Sen.
Facebook is not planning to release the ads to the public, and will not commit to sharing publicly greater details about the content of the ads and who they reached. Schiff said he intends to publish a representative sample of the ads.
Mr Zuckerberg initially said it was "crazy" to think that misinformation spread on Facebook influenced the outcome of the election, but he has now changed that view.
Twitter's decision to share that information with Congress followed a report by the US government's top intelligence agencies, which slammed RT in January as the "Kremlin's principal worldwide propaganda outlet".
Though Twitter disclosed last week that the company found over 200 Russian accounts linked to propaganda pages.