President Donald Trump on Wednesday said Facebook Inc. was biased against him during the election, marking the second time he has sought to rebut the notion that possible manipulation of the social network could have played a role in his election win.
The heated rhetoric comes as public scrutiny of the role of technology companies played in the election is set to heat up. On Wednesday, the Senate Intelligence Committee invited Facebook Inc., Alphabet Inc.'s Google and Twitter Inc. to testify on Nov. 1 about Russian interference on their platforms, according to people familiar with the matter.
The House Intelligence Committee said it would also hold a hearing with tech companies in October, but it has not yet determined a witness list or a date for the event. Both panels are probing Russian activity during the 2016 election.
Rep. Adam Schiff (D, Calif.), the top Democrat on the House Intelligence Committee, said in the hearings he believed the public would get a look at the actual ads bought by Russia.
"I'd like the public to be able to see the ads so cynically used to try to divide Americans against other Americans," Mr. Schiff said in an interview.
The public hearings follow closed-door sessions between Facebook and congressional investigators that took place earlier this month about the $150,000 in Russian-backed ads that appeared on Facebook during the campaign. Facebook confirmed that it received the Nov. 1 invitation.
Twitter is due to meet with House and Senate investigators behind closed doors on Thursday. A person close to the company confirmed Twitter's invitation to the Nov. 1 meeting.
Google didn't respond to requests for comment.
Amid Facebook's disclosures to Congress, President Trump has intensified his attacks on the social network. "Facebook was always anti-Trump," Mr. Trump said in a post on his Twitter account Wednesday, suggesting that Facebook was taking part in a media campaign against him. "The Networks were always anti-Trump hence, Fake News, @nytimes (apologized) & @WaPo were anti-Trump. Collusion?"
In response, Facebook Chief Executive Mark Zuckerberg said both liberals and President Trump are upset about ideas and content they don't like on Facebook. "That's what running a platform for all ideas looks like," Mr. Zuckerberg said in a post on Facebook in response to President Trump's tweet.
Mr. Trump has expressed skepticism about the intelligence community's findings that Russia interfered in the U.S. election, and has called the investigation into Moscow's role and related issues a "witch hunt." He has denied his campaign colluded with Russia, and Russia has denied interfering in the election.
After the election, Mr. Zuckerberg said misinformation on Facebook changing the outcome of the election was a crazy idea. On Wednesday, he backpedaled from this position and said he regretted the comment.
"This is too important an issue to be dismissive," he wrote in his post on Facebook.
Facebook has previously faced criticism for a perception it is left-leaning. Last May, Facebook faced allegations that its workers had a liberal bias in how they ranked the social network's popular topics. Although Facebook said an internal investigation found "no evidence of systematic political bias," it revamped how the feature works.
In December 2015, Mr. Zuckerberg ruled that Mr. Trump's posts should remain on the site, disagreeing with some employees who argued that some of Mr. Trump's posts should be removed for violating the site's rules on hate speech.
Mr. Trump's campaign used Facebook to reach voters in a targeted way. Its ads drew more engagement on Facebook, in the form of clicks and other signals, than those of Hillary Clinton's camp, according to people familiar with the internal figures.
The president criticized the company last October, several days before the election, when he said, in a post on his Twitter account, that Facebook, Twitter Inc. and Alphabet Inc.'s Google were "burying the FBI criminal investigation" of Mrs. Clinton.
By Georgia Wells and Byron Tau