Trump said he has told his administration to look for regulations and legislation that could protect free speech - though he did not provide details on what measures were being discussed - and said he would summon major social firms to the White House for talks in coming weeks.

"We're not going to be silenced," Trump said, complaining about fluctuations in the number of his Twitter followers. "Big tech must not censor the voices."

Freedom of speech is enshrined in the First Amendment of the U.S. Constitution.

Trump, who regularly lashes out at the mainstream news media for their work which he brands as "fake news," made social media a key part of his 2016 run for office as well as his 2020 reelection campaign. But he and other Republicans have long claimed that online platforms employ tactics to silence their voices, allegations that major social media companies have denied.

Dozens of pro-Trump online personalities convened in the stately East Room to discuss what they say is censorship on social media platforms, rubbing elbows with several members of Trump's cabinet and his White House team, and his son Donald Trump, Jr.

Amid the sea of suits, several red Trump campaign hats and rubber bracelets popped out. Singer Joy Villa, who describes herself as a conservative activist, wore a flamboyant stars-and-stripes formal gown.

Trump called to the stage Lila Rose, an anti-abortion activist who has been blocked from Pinterest; California lawyer Harmeet Dhillon, who has represented conservatives in free-speech lawsuits; and Lynnette Hardaway and Rochelle Richardson, sisters and video bloggers who are better known as Diamond and Silk.

Carpe Donktum, a pro-Trump online persona who was recently suspended by Twitter for eight days over a video depicting Trump as a cowboy attacking CNN journalist Jim Acosta, said the face-to-face event could unite online conservatives.

In freewheeling remarks that bounced from one topic to another - not unlike his Twitter feed followed by more than 61 million people - Trump talked about the power of social media, and railed against the traditional media standing at the back of the room.

"We hardly do press releases anymore," Trump said. "If I put it out on social media, it's like an explosion."

Trump acknowledged criticism about the online behavior of some conservative users of social media. "Some of you guys are out there - but even you should have a voice," Trump said.

"The crap you think of is unbelievable," he said. "I mean it's genius - but it's bad."

Trump more than once has threatened retaliatory action related to free speech. In March he signed an executive order requiring U.S. colleges and universities to maintain "free speech" on campus if they want to continue receiving federal research funds, and last September he suggested that the license of television network NBC could be challenged over its news reporting.

Senator Mark Warner, a Democrat, said that instead of focusing on "combating Russian social media misinformation, punishing anti-competitive practices, or protecting Americans' data and privacy, the president has invited trolls, conspiracy theorists, anti-Semites, and the whole comments section to the White House."

Trump said he might invite some of the conservative social media users back to the White House for the meeting with major social media firms. Three tech officials said they had no knowledge of the meeting before Trump announced it.

Facebook Inc, Twitter Inc and Alphabet Inc's Google declined to comment on Trump's announcement that he would bring them to the White House for a meeting.

The Internet Association, a trade group representing major tech firms like Facebook, Twitter and Google, said, "Internet companies are not biased against any political ideology, and conservative voices, in particular, have used social media to great effect."

Republicans in Congress have held numerous hearings on the issue of alleged conservative bias on social media outlets.

Republican Senator Josh Hawley, who is working on proposed legislation on the issue, took the stage briefly on Thursday to air his complaints.

"They've gotten rich off of their special privileges from government. They want to keep those, they shouldn't discriminate. They shouldn't censor," Hawley said.

A Senate panel chaired by Republican Ted Cruz on Tuesday will hold a hearing titled "Google and Censorship through Search Engines" featuring Google's vice president of public policy, Karan Bhatia.

REUTERS