The top Democrat on the House Intelligence Committee said Wednesday that representatives from social media companies, like Facebook and Twitter, should appear before the panel as part of its investigation into Russian election meddling.

“We do, I think, need the representatives of social media companies to come before our committee either in open or closed session,” Rep. Adam Schiff (D-Calif.) said, according to Reuters.

Schiff’s comments came a week after Facebook revealed that a company with ties to the Kremlin bought roughly $100,000 worth of ads on its platform between June 2015 and May 2017. 

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The ads were associated with some 470 inauthentic accounts that were likely operated out of Russia, Alex Stamos, Facebook’s chief security officer, wrote in a blog post.

The ads did not name a specific 2016 presidential candidate, but focused on divisive political issues ranging from gun control to immigration. 

Twitter is also expected to turn over to lawmakers an analysis of potential Russian activity on its platform. 

“It certainly appears that the Russians were engaged in a multipronged approach in using social media, through paid advertising, through paid event organizing, through dissemination and amplification of false and negative stories,” Schiff said, according to Reuters.

The U.S. intelligence community concluded in a report made public in January that the Kremlin sought to disrupt the 2016 election cycle with a hacking and influence campaign intended to sway the race in President Trump’s favor.

That conclusion sparked multiple congressional investigations, as well as a special counsel probe. Bloomberg reported earlier Wednesday that special counsel Robert Mueller has focused increasingly on Russia’s use of social media to sway public opinion and meddle in the election.