Updated 2.50pm with new Trump tweet
Donald Trump has unleashed a new tirade against his critics, dismissing allegations he is unfit to be president and proclaiming himself to be a "very stable genius".
The US president hit back after an explosive account of life at the White House claimed he never intended to enter the Oval Office and his staff believed he was not fit to hold high office.
The publication of Fire and Fury: Inside the Trump White House by Michael Wolff has already provoked a very public rift with his former strategist, Steve Bannon, who was one of the main sources of the book.
WATCH: Wolff's book is 'full of lies', White ouse says
In his latest online onslaught, Mr Trump accused his critics of trying to make an issue of his "mental stability and intelligence".
"Now that Russian collusion, after one year of intense study, has proven to be a total hoax on the American public, the Democrats and their lapdogs, the Fake News Mainstream Media, are taking out the old Ronald Reagan playbook and screaming mental stability and intelligence," he wrote in a series of trademark tweets.
"Actually, throughout my life, my two greatest assets have been mental stability and being, like, really smart. Crooked Hillary Clinton also played these cards very hard and, as everyone knows, went down in flames.
I went from VERY successful businessman, to top T.V. Star to President of the United States (on my first try). I think that would qualify as not smart, but genius....and a very stable genius at that!"
As the book shot to the top of the online bestseller lists in the US, White House spokeswoman Sarah Huckabee Sanders continued to dismiss the claims of a dysfunctional presidency which have gripped the American public.
Speaking on US television on Friday, she said that Mr Wolff had never interviewed Mr Trump despite having "repeatedly begged to see the president", describing him as "a guy who made up a lot of stories to try and sell books".
Mr Wolff however insisted that he "absolutely" spoke to the president, adding whether he "realised it was an interview or not, I don't know, but it was certainly not off the record"