President Trump defended his mental health again at a press conference on Saturday, saying his Ivy League education, television fame and 2016 election win are proof he is more than competent to run the country.

Responding to claims in Michael Wolff's new book Fire and Fury that White House insiders worry he is suffering mental decline, the president fired back and said he was never interviewed for it - hours after declaring himself a 'very stable genius' on Twitter.

'It's a disgrace that he can do something like this,' said Trump said of Wolff, who he called a 'fraud' as he attacked the libel laws in the United States at a Camp David press conference attended by GOP leaders.

Not happy: Trump (pictured at Camp David with the Republican leadership) attacked Fire and Fury author Michael Wolff for his book that alleges the president's White House is in disarray

A steely Trump dubbed Michael Wollf a fraud and said that he never gave an interview to the New York City journalist

'Libel laws are very weak in this country. If they were stronger, hopefully, you would not have something like that happen,' said Trump who had defended his intelligence just moments before.

'Only because I went to the best colleges, I was an excellent student, came out and made billions and billions of dollars and became one of the top business people, went to television and was a tremendous success, as I am sure you all know and ran for president first time and won.'

'And then this guy who doesn't know me, doesn't know me at all. Who said he interviewed me for three hours in the White House, it didn't exist, it's in his imagination.'

'He was never in the Oval Office,' said the president who blamed 'Sloppy' Steve Bannon for bringing him into the White House.

Trump then dubbed the biography 'a work of fiction'.

Earlier on Saturday, Wolff, who is a contributor to the Hollywood Reporter, gave that publication a follow up interview on Saturday in which he said he knew Trump was apoplectic with rage over the book.

'I hear that the president is very angry, or, let me be precise: I hear that he is truly bouncing off the walls,' said Wolff to the magazine.

Talking about the now-infamous dinner-party attended by former Fox CEO Roger Ailes, Steve Bannon and Hollywood Reporter co-owner Janice Min, Wolff said he recalled they ate clams and Arctic char.

Revealing that 100 percent of Trump's inner circle believe the president to be 'hopeless', Wolff also claimed that he got such unfettered access to the West Wing because essentially no one knew who he was because they don't read, especially Trump.

'People tell him what's in an article — that's what Hope Hicks does — and she probably told him it was great. It's easier if he thinks it's great,' said Wolff.

This came hours after Wolff declared in a BBC interview that his instant New York Times bestseller would prove the catalyst for the end of the Trump administration, which has not yet completed one year in office.

President Donald Trump repeated his attacks on author Michael Wolff (right, out in NYC on Friday) and 'sloppy' Steve Bannon

Striking back: Donald Trump launched off a series of early morning tweets on Saturday

Anger: The president was defending himself against claims that he is unfit to be in the Oval Office

Boasts: Trump declared himself to be a genius in his series of posts - and attacked favorite target Hillary Clinton too

The controversial journalist told the Today program, 'I think one of the interesting effects of the book so far is a very clear emperor-has-no-clothes effect.'

This was followed by one of Trump's now-traditional Saturday morning barrage of tweets - claiming that he is fit to be president and not just smart, but a 'genius... and a very stable genius at that!'

Hours before this, Wolff told the BBC's Today program: 'The story that I have told seems to present this presidency in a way that it says he can't do his job.

'Suddenly everywhere people are going, 'Oh my God, it's true, he has no clothes.'

He said the book was making people realise what the president was like.

When asked about what impact he expected the book would have, he said: 'We will end this presidency now.'

The journalist's book - 'Fire and Fury' has already shot to the top of the New York Times bestseller's list and portrays Trump as an imbecile who never believed he would win the 2016 election.

The book also severely questions the president's ability to carry out his job and casts aspersions on his mental acuity amid suggestions from White House sources he might be losing his mind.

Under fire: President Donald Trump departs for Camp David from the White House in Washington on Friday afternoon

The fallout sparked Trump onto Twitter to defend his mental fitness and boast about his intelligence.

It's his latest pushback against a book that portrays him as a leader who doesn't understand the weight of the presidency.

In the book, former aide Steve Bannon questions Trump's competence.

Trump's was having none of it.

He wrote that critics are 'taking out the old Ronald Reagan playbook and screaming mental stability and intelligence.'

Trump modestly added, 'my two greatest assets have been mental stability and being, like, really smart.'

Furthermore Trump opined that he was a successful businessman to reality TV star to president on his first try 'would qualify as not smart, but genius .... and a very stable genius at that!'

Another target: Trump aimed an attack on Brian Ross - who erroneously reported that the president had nefariously ordered Michael Flynn to contact the Russians

During the course of his 15-minute interview with the BBC, Wollf repeated many of his previous claims about Trump, his White House and defended his book from claims of inaccuracy.

'Everyone went into election night expecting not to win. It would have been a victory to have kept their loss (to Hillary) to under six points,' said Wolff to the BBC.

'It was only around 8.15pm (on election night in 2016) that the trends started to really go the other way and come to terms with the fact that they were going to win.

'And by all reports the person most shocked by this was Trump's wife Melania, who certainly didn't want to be First Lady. Second to her it was Trump himself who appeared to be white as a ghost.'

Denying Trump's claim that he was given zero access and that the book was completely false, Wolff claimed he spent months in the West Wing, literally sitting on a sofa watching the West Wing and definitely got tacit permission from the president.

'I went the time honored fashion and I spoke to everyone who is as close to the action as possible who will talk to you. And you often grant them the veil of anonymity,' said Wolff.

'I got the president to say 'If not welcome, here, come in', then he certainly seemed to shrug his shoulders and say 'yea, if that's what you want to do then fine.'

Revealing that Trump's tantrums and volcanic temper are as much bemusing as intimidating, Wolff said that the White House resembled a side-show at times.

'One of the things about Donald Trump is that everything he does is Trumpian and that is one of the amusing things and one of the disconcerting things,' said Wolff to the BBC.

'It is theatric - he screams, he is yelling. What starts out as a schtick turns into vein popping rage.

'Every person in the White House describes him as child-like. That the president is in some way like a child. Sometimes it's an 11-year-old, sometimes its a six-year-old and sometimes it's a two-year-old. It's his need for immediate gratification.'

Worryingly, Wolff claims that despite entering the White House on a swell of euphoria - at least from his base - Trump does not have the faith of his cabinet anymore.

'All the senior staff have come to the conclusion over eight months that something was unbelievably amiss here - this was more peculiar than they ever imagined it could be and that in the end they had to look at Donald Trump and say, 'No, this man can't function in this job.' said Wolff.

'He may have been elected president but that does not turn him into president.'

Discussing the most shocking claim in Wolff's book - that of the president's mental health, Wolff said that it is not for him to say, but West Wing insiders are worried.

'Is he experiencing fundamental physical and mental issues?' said Wolff.

'All I can say is that it's a subject discussed in the White House and it is a subject of concern because his repetitions have been so frequent that people around him are saying, 'Oh my God, what are we going to do?'

The Saturday-morning tweet-barrage defending his own mental competency launched by Trump followed two other posts, one praising news the country's African-American unemployment rate had fallen to its lowest rate on record.

The president’s tweet was a response to a tweet put out by the official Republican Party Twitter account which uses quotes from other journalists to call into question Wolff's credibility

He then attacked ABC reporter Brian Ross, who has returned to the network after a month-long suspension for reporting in error that Trump had ordered his former national security adviser Michael Flynn to collude with the Russians.

Trump said that Ross should have lost his job over his error.

These tweets followed last night's further attack on Steven Bannon in which he accused his former Chief Strategist of crying when he lost his job.

Hitting out at 'sloppy Steve Bannon,' tweeting that he 'cried when he got fired and begged for his job.'

'Now Sloppy Steve has been dumped like a dog by almost everyone,' Trump tweeted.

'Too bad!'

The president's tweet was a response to a tweet put out by the official Republican Party Twitter account.

Difficult years: Michael Wolff's biography also made the claim that Trump has been 'chronically' unfaithful to his wife Melania

The GOP's Twitter handle posted an image of Wolff, saying 'the reviews are in.'

It then lists a number of quotes made about Wolff by journalists who have questioned his credibility.

Wolff has been accused in years past of fabricating details in books and misrepresenting events.

Bannon joined an exclusive club Thursday night, earning the derogatory nickname 'Sloppy Steve' from Trump.

Shortly after initial claims from the book were published, the president on Tuesday tweeted that the political gossip tome is 'full of lies, misrepresentations and sources that don't exist.'

'Look at this guy's past and watch what happens to him and Sloppy Steve!'

The former White House chief strategist dresses 'like an unmade bed,' a close associate told DailyMail.com on Friday, 'and doesn't care'

Bannon is known for dressing 'like an unmade bed and doesn't care,' a close associate told DailyMail.com on Friday, layering two polos on top of each other.

He eschewed suits and other business attire outside the White House when he worked for the president.

Wolff describes Bannon's typical attire as a 'disheveled blazer' and 'signature pairing of two shirts and military fatigues.'

Sources claim Trump's closest allies questioned his suitability for office and view him as a 'child'.

Trump's lawyers made threats of legal action and tried to stop Henry Holt & Co from publishing the critical book which the president has dismissed as full of lies.

Trump, 71, attacked Wolff and former top aide Steve Bannon, who was quoted in the book, on Twitter on Friday night.

Wolff is the author of 'Fire and Fury: Inside the Trump White House'

He wrote: 'Michael Wolff is a total loser who made up stories in order to sell this really boring and untruthful book.

'He used Sloppy Steve Bannon, who cried when he got fired and begged for his job.

'Now Sloppy Steve has been dumped like a dog by almost everyone. Too bad!'

The book claims Bannon called a meeting involving the president's son, Donald Trump Jnr, and son-in-law, Jared Kushner, with a Russian lawyer during the 2016 presidential campaign 'treasonous'.

The meeting is being probed as part of an investigation into possible collision between Trump's presidential election campaign and Russia.

After the comments attributed to Bannon were made public, Trump said his former strategist had 'lost his mind'.

Trump's lawyer has said that legal action is 'imminent' against Bannon.