Twitter places "public interest" notices on some rule-breaking tweets from "world leaders" that would otherwise be removed.

Such tweets from political candidates and elected or government officials are instead hidden by a warning and Twitter takes actions to restrict their reach.

But the company said this treatment does not apply to former office holders.

"This policy framework applies to current world leaders and candidates for office, and not private citizens when they no longer hold these positions," a Twitter spokesman said in a statement.

It has added multiple warnings and labels to tweets from the @realDonaldTrump account, including many since Tuesday's election that made unfounded allegations of voting fraud.

It first hid one of his tweets behind a "public interest" label in May when the president violated the company's policy against glorifying violence.

Under Facebook Inc's policies, it appears that after Biden takes office in January, Trump's posts would also no longer be exempt from review by Facebook's third-party fact-checking partners.

Facebook's online policy says it defines politicians, whose posts are exempt from fact-checking, as candidates running for office, current office holders and many of their cabinet appointees, along with political parties and their leaders.

It says "former candidates for office or former officials continue to be covered by our third-party fact-checking programme."

Facebook did not reply to Reuters questions about how it would treat Trump's account.

Biden's victory on Saturday in Pennsylvania put the Democratic presidential candidate over the threshold of 270 Electoral College votes needed to clinch the presidency.

Republican Trump has not conceded and has vowed to challenge the outcome in court.

Australian Associated Press