President Trump criticized Facebook, Google and Twitter on Thursday for what he called "terrible bias" and accused tech giants of censoring conservatives.

Trump didn't invite Facebook (FB) , Twitter (TWTR) or YouTube (owned by Google) (GOOG) to a "social media summit" held Thursday at the White House, but did invite various right-wing publishers, according to published reports.

A story in the Washington Post related to the event quoted the president as saying about those social media platforms, "Some of you are extraordinary. The crap you think of is unbelievable."

According to a report from The Associated Press, Trump told the conservative critics of social media that they've successfully used the platforms to send messages directly to the American people without going through the "fake news filter."

The Post reported that Democratic lawmakers and watchdog groups were concerned that Trump had invited supporters who have a history of targeting the president's political opponents on Twitter, and through misleading videos and conspiracy theories.

The Post report also quoted Democratic Sen. Mark Warner of Virginia as saying, "This has the appearance not of a social media summit but a political rally and call for the right. The fact that some of the most extreme voices on social media are coming to the White House, and they get a forum to complain about how often they're retweeted, and that the actual platform companies aren't even invited, smacks of the absurd."

The Southern Poverty Law Center, meanwhile, said that the president is "essentially conducting a hate summit at the White House," said Heidi Beirich, the director of the group's work to track online extremism.

Earlier Thursday, Trump took to one of the companies he criticized -- Twitter -- to attack what he called the "Fake News Media."

A big subject today at the White House Social Media Summit will be the tremendous dishonesty, bias, discrimination and suppression practiced by certain companies. We will not let them get away with it much longer. The Fake News Media will also be there, but for a limited period..

— Donald J. Trump (@realDonaldTrump) July 11, 2019

This article was written by a staff member of TheStreet.