Donald Trump has slammed his former chief strategist and election campaign CEO Steve Bannon, accusing him of having 'lost his mind'.
It comes after media outlets published quotes by Bannon - who is currently the executive chairman of the far-right Breitbart News site - from an upcoming book.
Bannon was seen as one of the key people behind the Trump campaign, and has been an outspoken opponent of establishment Republicans.
He recently backed controversial Alabama Senate candidate Roy Moore - who suffered a shock defeat to Democrat Doug Jones.
The Guardian reported that Bannon, who left his White House role last August, has now told author Michael Wolff that the controversial Trump Tower meeting between senior campaign officials and several Russians was 'treasonous' and 'unpatriotic'.
He reportedly said: "The three senior guys in the campaign thought it was a good idea to meet with a foreign government inside Trump Tower in the conference room on the 25th floor – with no lawyers. They didn’t have any lawyers.
"Even if you thought that this was not treasonous, or unpatriotic, or bad s**t, and I happen to think it’s all of that, you should have called the FBI immediately."
Trump's son, Donald Jr, was at the meeting, and Bannon claimed US investigators are "going to crack Don Junior like an egg on national TV".
The comments appeared to provoke a strong from President Trump, who had last year thanked Bannon 'for his service'.
I want to thank Steve Bannon for his service. He came to the campaign during my run against Crooked Hillary Clinton - it was great! Thanks S
— Donald J. Trump (@realDonaldTrump) August 19, 2017
In a written statement provided to US media outlets today, Trump said: "Stephen K Bannon has nothing to do with me or my Presidency. When he was fired, he not only lost his job, he lost his mind. Steve was a staffer who worked for me after I had already won the nomination by defeating seventeen candidates, often described as the most talented field ever assembled in the Republican party.
"Now that he is on his own, Steve is learning that winning isn’t as easy as I make it look. Steve had very little to do with our historic victory, which was delivered by the forgotten men and women of this country. Yet Steve had everything to do with the loss of a Senate seat in Alabama held for more than thirty years by Republicans. Steve doesn’t represent my base — he’s only in it for himself."
He goes on to accuse Bannon of "leaking false information to the media" during his time at the White House "to make himself seem far more important than he was".
Trump added: "Steve was rarely in a one-on-one meeting with me and only pretends to have had influence to fool a few people with no access and no clue, whom he helped write phony books."
The upcoming book, Fire And Fury: Inside The Trump White House, also prompted strong criticism from White House press secretary Sarah Huckabee Sanders, who claimed the book was filled with 'false and misleading accounts'.
Sanders statement on Wolff book: “This book is filled with false and misleading accounts from individuals who have no access or influence with the White House."
— Jim Acosta (@Acosta) January 3, 2018