Twitter said Mr Trump’s refusal to attend Mr Biden’s inauguration was being received by his supporters as “further confirmation that the election was not legitimate” and him disavowing his previous claim there would be an “orderly transition”.
It claimed one of his tweets may also “serve as encouragement to those potentially considering violent acts that the inauguration would be a ‘safe’ target, as he will not be attending”.
The use of the words “American Patriots” to describe some of his supporters was also being interpreted as support for those committing violent acts at the US Capitol, Twitter said.
It added: “Plans for future armed protests have already begun proliferating on and off Twitter, including a proposed secondary attack on the US Capitol and state capitol buildings on January 17, 2021.
“As such, our determination is that the two tweets … are likely to inspire others to replicate the violent acts that took place on January 6, 2021, and that there are multiple indicators that they are being received and understood as encouragement to do so.”
Following the ban, Twitter deleted two tweets apparently issued by Mr Trump on the @POTUS account, and also suspended the @TeamTrump account after it spread a statement from the president.
The statement said: “After close review of recent tweets from the @realDonaldTrump account and the context around them – specifically how they are being received and interpreted on and off Twitter – we have permanently suspended the account due to the risk of further incitement of violence.
“In the context of horrific events this week, we made it clear on Wednesday that additional violations of the Twitter rules would potentially result in this very course of action. Our public interest framework exists to enable the public to hear from elected officials and world leaders directly. It is built on a principle that the people have a right to hold power to account in the open.
“However, we made it clear going back years that these accounts are not above our rules entirely and cannot use Twitter to incite violence, among other things.
“We will continue to be transparent around our policies and their enforcement.”
Facebook removed a short video on January 6 that Mr Trump had posted to his social media accounts.
Facebook’s vice president of integrity, Guy Rosen, said the action was taken “because on balance we believe it contributes to rather than diminishes the risk of ongoing violence”.
Later that day, the site blocked his ability to post new content. Then on January 7, it said he would remain blocked until his term in the White House concluded on January 20.
Mr Trump is planning to address his “deplatforming” by social media companies on Monday January 11, reportedly seeking ways to bring them to heel before leaving office.
It comes as apps including preferred conservative messaging site Parler were removed altogether by tech giants for allowing “threats of violence” after the storming of the US Capitol.
How Washington reacted
The House of Representatives has voted to impeach Donald Trump, making him the first president in US history to be impeached twice.
Ten Republicans joined Democrats in voting for impeachment over Mr Trump’s role riling up the mob.
The article, which charging him with “incitement of insurrection”, carried by 232 votes to 197.
Mr Trump will now face a trial in the Senate.
Nancy Pelosi and Chuck Schumer, the Democratic Party leaders in the US House of Representatives and Senate respectively, demanded Mr Trump’s immediate removal amid outrage at his actions before the US Capitol was stormed by a mob of his supporters.
They publicly called on Mike Pence, the US vice president, to invoke the 25th Amendment, a mechanism that removes a president who is “unable to discharge the powers and duties of his office”, but Mr Pence refused.
A wave of top officials quit the White House, turning their backs on Mr Trump.
A number of White House staff, including Sarah Matthews, the deputy press secretary, and Stephanie Grisham, Melania Trump’s chief of staff, resigned effective immediately. It was also reported that Chris Liddell, the president’s deputy chief of staff, had quit.
How the world reacted
Boris Johnson called on the US to restore the rule of law. “Disgraceful scenes in US Congress”, the British prime minister tweeted.
“The United States stands for democracy around the world and it is now vital that there should be a peaceful and orderly transfer of power. “
EU officials expressed shock at the “assault on US democracy”.
“To witness tonight’s scenes in Washington DC is a shock,” European Council president Charles Michel tweeted.
“In the eyes of the world, American democracy tonight appears under siege,” the European Union’s foreign policy supremo Josep Borrell said, in a separate tweet.
“This is an unseen assault on US democracy, its institutions and the rule of law. This is not America. The election results of 3 November must be fully respected,” Mr Borrell said, referring to the US presidential election that saw Mr Trump beaten by Joe Biden.
“The strength of US democracy will prevail over extremist individuals,” Mr Borrell said.
Speaking to Sky News, Kim Darroch, the UK’s former ambassador to the US, shared his belief that Mr Trump was not fit to be president, before suggesting No 10 “got too close” to the Trump presidency.
The German Chancellor, Angela Merkel, announced she is “furious and saddened” by the violence seen in Washington DC, and said Mr Trump shares the blame for the unrest among his supporters.
“I deeply regret that President Trump has not conceded his defeat, since November and again yesterday,” she said, before adding: “Doubts about the election outcome were stoked and created the atmosphere that made the events of last night possible.”