US President Donald Trump's lawyers have said that the BBC must retract the Panorama documentary by 14 November or face a lawsuit for "no less" than $1 billion, according to a letter sent yesterday.
Mr Trump sent a letter to the BBC threatening legal action over the way a documentary aired edited clips of his speech just before the 2021 US Capitol assault.
A BBC spokesperson said: "We will review the letter and respond directly in due course."
BBC chair Samir Shah previously said the corporation has received communication from Mr Trump over the editing of the Panorama documentary, broadcast the week before last year's US election, but did not confirm the US president has threatened to sue.
He said: "We are now considering how to reply to him."
Asked directly if Mr Trump has said he will be suing the BBC, Mr Shah said: "I do not know that yet, but he's a litigious fellow so we should be prepared for all outcomes."
Earlier, Mr Shah apologised for an "error of judgement" in editing the speech.
The apology follows the resignation of two of the corporation's most senior figures yesterday - chief executive of BBC News Deborah Turness and director-general Tim Davie - who announced their departure from the BBC after concerns were raised in a memo.
Mr Shah said the BBC had reviewed the footage and acknowledged it should have been clearer about changes made to the original remarks.
"It is absolutely clear the BBC must champion impartiality," Mr Shah wrote to British MPs, adding that the broadcaster is committed to restoring public trust and ensuring its journalism meets the highest standards of fairness.
Mr Shah, who was responding to a letter from the UK's Culture, Media and Sport Committee, said there have been more than 500 complaints since the publication of the memo, adding: "We accept that the way the speech was edited did give the impression of a direct call for violent action."
The memo by Michael Prescott, a former external adviser to the BBC's editorial standards committee, raised concerns in the summer about the way clips of the US president's speech on 6 January 2021 were spliced together in 'Trump: A Second Chance?' to make it appear Mr Trump had told supporters he was going to walk to the US Capitol with them to "fight like hell".
Earlier, Ms Turness stressed the corporation is "not institutionally biased" and the journalists are not "corrupt".
Arriving at Broadcasting House in central London, she told reporters: "I would like to say it has been the privilege of my career to serve as the CEO of BBC News and to work with our brilliant team of journalists.
"I stepped down over the weekend because the buck stops with me.
"But I'd like to make one thing very clear, BBC News is not institutionally biased. That's why it's the world's most trusted news provider."
Asked if BBC journalists are institutionally corrupt, she replied: "Of course our journalists aren't corrupt, our journalists are hard working people who strive for impartiality, and I will stand by their journalism.
"There is no institutional bias. Mistakes are made, but there's no institutional bias."
Asked why mistakes were not dealt with, including on Mr Trump, on antisemitism and on women's rights, Ms Turness replied: "I'm sure that story will emerge."
Critics said the Panorama documentary, broadcast by the BBC the week before last year's US election, was misleading and removed a section where the US president said he wanted supporters to demonstrate peacefully.
Mr Shah said yesterday was a "sad day" for the BBC while committee chairwoman Caroline Dinenage said Mr Davie's resignation was "regrettable" but "restoring trust in the corporation must come first".
Mr Davie said his departure will not be immediate and that he is "working through" timings to ensure an "orderly transition" over the coming months, while Ms Turness said controversy around the Panorama edit had "reached a stage where it is causing damage to the BBC - an institution that I love".
In a statement sent to staff, Mr Davie said his resignation was "entirely" his decision and he was "thankful" to the chairman and board for their "unswerving and unanimous support" during his tenure.
He said: "Like all public organisations, the BBC is not perfect, and we must always be open, transparent and accountable."
The BBC has been criticised for a number of failings in recent months which include breaching its own accuracy editorial guidelines, livestreaming the controversial Bob Vylan Glastonbury set, as well as misconduct allegations surrounding former MasterChef presenter Gregg Wallace.
