Donald Trump has claimed Steve Bannon ”cried when he was fired and begged for his job", marking an escalation in the feud between the former strategist whose contributions to an explosive new book have made headlines around the world.

The US President also branded author Michael Wolff “a total loser who made up stories” to sell copies of his purported tell-all account of the billionaire’s first year in the White House.

Mr Trump took aim at the pair on Twitter, returning to his favoured method of attack after his legal team failed to halt the publication of Fire and Fury: Inside the Trump White House, which shot to the top of bestseller lists before release on Friday.

“Michael Wolff is a total loser who made up stories in order to sell this really boring and untruthful book,” wrote the American leader.

“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 President’s attack on Mr Bannon marked a further deterioration of his relationship with his former confidante.

Mr Trump is said to have felt infuriated and betrayed when Fire and Fury excerpts emerged this week in which the Breitbart News executive chairman described a meeting between the President’s eldest son and Kremlin-linked Russian lawyer as “treasonous”.

Mr Bannon also portrayed the Republican as out of his depth, with the instincts of a child, and said the President’s team White House possessed no “brain trust”.

In response, Mr Trump claimed his ex-strategist had “lost his mind” and “had very little to do with our historic victory”,

“Steve Bannon has nothing to do with me or my Presidency,” Mr Trump said in a statement. “When he was fired, he not only lost his job, he lost his mind.”

Mr Trump’s lawyers also sent a cease and desist letter to Mr Bannon, accusing him of breaking his employment agreement and defaming the President.

As the American leader retreated to the woods of Camp David to discuss legislative priorities with senior Republicans this weekend, his administration and party continued efforts to discredit Mr Wolff’s book.

White House press secretary Sarah Huckabee Sanders said Fire and Fury was full of errors and claimed even journalists who had been critical of the administration believed Mr Wolff had damaged the credibility of the media.

“This is a guy who made up a lot of stories to try and sell books,” she told Fox News, while the Republican National Committee tweeted a mocked-up book cover with the headline “Liar and Phony”.

Michael Wolff, author of explosive Donald Trump book, describes inner circle view of President

Some journalists have also pointed out factual inaccuracies in the book.

Mark Berman, a Washington Post reporter who Mr Wolff writes of eating breakfast in the Four Seasons at the same time as Ivanka Trump, said he had “never actually been there” and that he was attending the birth of his child on the day in question.

The reporter later added he believed he had been mistakenly named instead of lobbyist Mike Berman.

Mr Wolff himself concedes in author’s note some of what his sources told him was untrue.

“Many of the accounts of what has happened in the Trump White House are in conflict with one another; many, in Trumpian fashion, are baldly untrue,” he writes. "These conflicts, and that looseness with the truth, if not with reality itself, are an elemental thread of the book."

He adds: “Sometimes I have let the players offer their versions, in turn allowing the reader to judge them. In other instances I have, through a consistency in the accounts and through sources I have come to trust, settled on a version of events I believe to be true.”

In an NBC interview, the veteran journalist said he has recordings and notes and remains “absolutely in every way comfortable with everything I’ve reported in this book”.

Complaints from Mr Trump's camp have done nothing to impede the book's popularity.