Facebook has told investigators that it discovered thousands of political ads published on its platform over the past two years were linked to fake accounts based in Russia.

Alex Stamos, Facebook's chief security officer, made the revelation in a blog post Wednesday. Stamos said that 470 inauthentic accounts spent about $100,000 to buy roughly 3,000 ads. He added that the accounts have since been suspended.

According to Facebook, the majority of the ads did not reference either of the two presidential candidates last year but were largely promoting divisive social issues, like immigration and gun control.

The Washington Post reported that Facebook had disclosed the findings to congressional investigators on Wednesday. According to the Post, Facebook told investigators that the accounts were all linked to a company called the Internet Research Agency, a "troll farm" that uses social media operations to promote Kremlin propaganda.

"We know we have to stay vigilant to keep ahead of people who try to misuse our platform," Stamos wrote. "We believe in protecting the integrity of civic discourse, and require advertisers on our platform to follow both our policies and all applicable laws. We also care deeply about the authenticity of the connections people make on our platform."

Reuters reported later on Wednesday that the information had also been turned over to Special Counsel Robert Mueller.

The company has refused requests from researchers to release data on political ad spending on its platform.

Sens. Richard Burr (R-N.C.) and Mark Warner (D-Va.), the chairman and ranking member of the Senate Intelligence Committee, respectively, have been in talks with Facebook officials as part of their investigation into Russia's efforts to influence last year's presidential election.

A Facebook spokesman told CNN in July that "we have seen no evidence that Russian actors bought ads on Facebook in connection with the election."

Stamos said on Wednesday that the political ads were bought by the fraudulent Russia-linked accounts between June 2015 and May of this year.

- This story was updated at 9:50 p.m.