Twitter is 'interfering' in the US election, 'stifling' free speech, says US President Donald Trump

US President Donald Trump has alleged that Twitter is "interfering" in the US election and "completely stifling" free speech, after the social media network placed a fact-checking warning on one of his tweets for the first time.

On Tuesday, Twitter added a warning phrase to two of Trump tweets that called mail-in ballots "fraudulent" and predicted that "mail boxes will be robbed,” among other things.

"Twitter is now interfering in the 2020 Presidential Election. They are saying my statement on Mail-In Ballots, which will lead to massive corruption and fraud, is incorrect, based on fact-checking by Fake News CNN and the Amazon Washington Post....," Trump tweeted on Tuesday.

"Twitter is completely stifling FREE SPEECH, and I, as President, will not allow it to happen!" he said in another tweet.

Twitter has introduced the new fact checking system to combat misinformation.

"Get the facts about mail-in ballots," read the message beneath each tweet and it took a reader to a new page having links to various news reports from media outlets like The Washington Post and the CNN.

"There is NO WAY (ZERO!) that Mail-In Ballots will be anything less than substantially fraudulent. Mail boxes will be robbed, ballots will be forged & even illegally printed out & fraudulently signed. The Governor of California is sending Ballots to millions of people, anyone.....," Trump had tweeted.

Soon thereafter, Twitter posted a message at the bottom of this tweet.

"Get the facts about mail-in ballots," Twitter said.

"Twitter has placed a fact-checking warning on a tweet issued by President Trump in which he claims without evidence that mail-in ballots are fraudulent," NPR reported.

Twitter spokesman Trenton Kennedy told the NPR that while the tweet about mail-in voting does not violate Twitter's rules since "it does not directly try to dissuade people from voting," it does contain "misleading information about the voting process, specifically mail-in ballots."

The Trump Campaign alleged that Twitter was interfering with the president getting his message through to voters.

"We always knew that Silicon Valley would pull out all the stops to obstruct and interfere with President Trump getting his message through to voters," Brad Parscale, Trump 2020 campaign manager said.

"Partnering with the biased fake news media ''fact checkers'' is only a smoke screen Twitter is using to try to lend their obvious political tactics some false credibility. There are many reasons the Trump campaign pulled all our advertising from Twitter months ago, and their clear political bias is one of them," Parscale said in a statement.