WASHINGTON, UNITED STATES -- U.S. President Donald Trump on Wednesday threatened to close down social media platforms after Twitter labelled two of his tweets "unsubstantiated" and accused him of making false claims.

Twitter targeted tweets in which the president said that mail-in voting would lead to fraud and a "Rigged Election" in November.

Under the tweets, Twitter posted a link which read "Get the facts about mail-in ballots" -- a first for the social network which has long resisted calls to censure the president.

In response, Trump fought back, tweeting that "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."

Trump repeated his allegations, saying "we can't let large scale Mail-In Ballots take root in our Country. It would be a free for all on cheating, forgery and the theft of Ballots.

"Whoever cheated the most would win. Likewise, Social Media. Clean up your act, NOW!!!!" he added.

The president also accused social media platforms of interfering in the last election, saying "we saw what they attempted to do, and failed, in 2016."

80 MILLION FOLLOWERS

The president has long used Twitter as a platform to spread abuse, conspiracy theories, false information and insults to his 80 million followers.

Before being elected in 2016, he built his political brand by supporting the "birther" lie that Barack Obama, America's first black president, was not born in the United States and therefore was not eligible to be president.

The notice tagged to Trump's tweets read "Trump falsely claimed that mail-in ballots would lead to 'Rigged Election'

"However, fact-checkers say there is no evidence that mail-in ballots are linked to voter fraud."

Trump aimed the misleading tweets at California, contending wrongly that anyone living in the state would be sent ballots when in fact they will only go to registered voters, according to the notice.

The tweets in question violated a recently expanded Twitter policy, said the San Francisco-based company.

"In serving the public conversation, our goal is to make it easy to find credible information on Twitter and to limit the spread of potentially harmful and misleading content," the company vowed when the change was announced.

Twitter's move came as Trump, already facing US economic calamity and 100,000 deaths from coronavirus as well as sinking reelection polls, continued to push a conspiracy theory about TV host Joe Scarborough.

In an attempted character assassination of Scarborough, Trump has spread the baseless rumor that Scarborough murdered an aide.

The entirely evidence-free story claims that Scarborough killed a woman he was having an affair with in 2001, when he was a Republican congressman and she was one of his staffers.