Former president Donald Trump is suing Facebook, Twitter and Google’s YouTube, as well as their respective chief executives, in lawsuits alleging “unlawful censorship” of Americans.

Trump on Wednesday said he would lead class actions against chief executives Mark Zuckerberg, Jack Dorsey and Sundar Pichai, as well their Big Tech platforms.

“We’re asking the US district court for the southern district of Florida to order an immediate halt to social media companies’ illegal shameful censorship of the American people,” he said, adding that he was also asking the court to restore his accounts and impose punitive damages.

“It will be a pivotal battle in the defence of the First Amendment. And in the end, I’m confident that we will achieve a historic victory for American freedom and at the same time, freedom of speech,” Trump said.

Twitter banned Trump from its platform permanently after the storming of Capitol Hill on January 6, citing repeated violations of its moderation policies and the risk that he could use it to incite further violence.

Facebook has banned Trump for at least two years on similar grounds, while Google’s YouTube has indefinitely suspended his account.

The moves have deprived the former president of vital mouthpieces he used to broadcast compulsively to his tens of millions of followers, excoriating his enemies, praising his allies and repeating baseless allegations of election fraud by his Democratic opponents over the 2020 election.

Throughout his presidency, Trump and many of his Republican allies argued that the Big Tech platforms were biased against conservatives, while leftwing critics of the platforms said that they failed to do enough to police hate speech.

The legal effort announced on Wednesday is supported by America First Policy Institute, a non-profit dedicated to promoting Trump’s policies.

The complaints for each case allege that Democrat legislators “coerced” the respective platforms by publicly calling to ban the former president and others, and threatening them with regulation and antitrust break-ups.

The lawsuits also allege that the platforms worked with “federal actors” to impose censorship — for example by partnering with the Centers for Disease Control and Prevention to “suppress contradictory medical views”.

The filings claim the social media networks violated the First Amendment, which guarantees free speech. They are also seeking a ruling that Section 230 of the Communications Decency Act, which gives tech platforms immunity from being sued over user-generated content, is unconstitutional.

Trump is named alongside a handful of other individuals as plaintiffs. The American Conservative Union is also named in the Twitter case.

The former president said he expected the litigation to be a “very, very important game changer for our country” and would “go down as the biggest class action ever filed, because thousands of people want to join”.

Nevertheless, some legal experts argued that the litigation was misguided, as under the First Amendment, platforms have the discretion to decide what speech they will host, while an individual does not have a constitutional right to use their services.

“Trump has the First Amendment argument exactly wrong,” said Paul Barrett, deputy director of the NYU Stern Center for Business and Human Rights. “The First Amendment applies to government censorship or speech regulation. It does not stop private sector corporations from regulating content on their platforms.”

Since the social media bans, Trump has struggled to cultivate similar online clout elsewhere. In May, he launched his own blog site — From the Desk of Donald J Trump — only to shut it down less than a month later, reportedly frustrated by a lack of readership. He is also exploring setting up his own social media platform.

A Twitter spokesperson declined to comment on the lawsuit. Facebook and Google did not immediately respond to a request for comment.