WASHINGTON (REUTERS, BLOOMBERG) - US President Donald Trump will sign an executive order on social media companies on Thursday (May 28), White House officials said after Mr Trump threatened to shut down websites he accused of stifling conservative voices.

The order could bring a flurry of lawsuits down on Twitter, Facebook and other technology giants by having the government narrow liability protections that they enjoy for third parties' posts, according to a draft of an executive order obtained by Bloomberg.

The companies' protections against lawsuits apply when they act "in good faith" in taking down or limiting the visibility of inappropriate tweets, videos and other social media posts, but the law doesn't define bad faith.

The draft order would push the Federal Communications Commission to issue rules clarifying the issue, potentially allowing users to sue over takedowns if they were inconsistent with companies' terms of service, did not provide enough notice or meet other suggested criteria.

The White House declined to comment early on Thursday morning.

The draft order would also convene, through the Justice Department, a working group of state attorneys general to look into deceptive practices and review executive ad spending on the platforms. The move could set off a legal battle between Washington and Silicon Valley.

The dispute erupted after Twitter on Tuesday for the first time tagged Mr Trump's tweets about unsubstantiated claims of fraud in mail-in voting with a warning prompting readers to fact check the posts.

Separately, a three-judge panel of the US Court of Appeals in Washington on Wednesday upheld the dismissal of a lawsuit by a conservative group and right-wing YouTube personality against Google, Facebook, Twitter and Apple accusing them of conspiring to suppress conservative political views.

In an interview with Fox News Channel on Wednesday, Facebook's Chief Executive Mark Zuckerberg said censoring a platform would not be the "right reflex" for a government worried about censorship.

Fox played a clip of the interview and said it would be aired in full on Thursday.

Facebook left Mr Trump's post on mail-in ballots on Tuesday untouched.

The American Civil Liberties Union said the First Amendment of the US Constitution limits any action Mr Trump could take.

Facebook and Google declined comment. Apple did not respond to a request for comment.

"Republicans feel that Social Media Platforms totally silence conservatives voices. We will strongly regulate, or close them down, before we can ever allow this to happen," Mr Trump said in a pair of additional posts on Twitter on Wednesday.

The president, a heavy user of Twitter with more than 80 million followers, added: "Clean up your act, NOW!!!!"

Republican Trump has an eye on the November election. "Big Tech is doing everything in their very considerable power to CENSOR in advance of the 2020 Election," Mr Trump tweeted on Wednesday night. "If that happens, we no longer have our freedom."

STRONGEST THREAT YET

Mr Trump's threat is his strongest yet within a broader conservative backlash against Big Tech. Shares of both Twitter and Facebook fell on Wednesday.

Last year the White House circulated drafts of a proposed executive order about anti-conservative bias which never gained traction.

The Internet Association, which includes Twitter and Facebook among its members, said online platforms do not have a political bias and they offer "more people a chance to be heard than at any point in history."

Late on Wednesday, Twitter CEO Jack Dorsey said Mr Trump's tweets about California's vote-by-mail plans "may mislead people into thinking they don't need to register to get a ballot."

Separately, Twitter said Mr Trump's tweets were labelled as part of efforts to enforce the company's "civic integrity policy." The policy document on Twitter's website says people may not use its services for manipulating or interfering in elections or other civic processes.

In recent years, Twitter has tightened its policies amid criticism that its hands-off approach allowed fake accounts and misinformation to thrive.

Tech companies have been accused of anti-competitive practices and violating user privacy. Apple, Google, Facebook and Amazon face antitrust probes by federal and state authorities and a US congressional panel.

Republican and Democratic lawmakers, along with the US Justice Department, have been considering changes to Section 230 of the Communications Decency Act, a federal law largely exempting online platforms from legal liability for the material their users post. Such changes could expose tech companies to more lawsuits.

Republican Senator Josh Hawley, a frequent critic of Big Tech companies, sent a letter to Twitter Chief Executive Jack Dorsey asking why the company should continue to receive legal immunity after "choosing to editorialise on President Trump's tweets."