Donald Trump has attacked his former chief strategist ahead of the release of a book that paints the US president as juvenile and his White House as chaotic.

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

Meanwhile, the president’s lawyer Charles Harder threatened legal action against Mr Bannon over “disparaging statements and in some cases outright defamatory statements”.

Mr Harder sent a letter to Mr Bannon saying the former aide violated confidentiality agreements by speaking with the book’s author Michael Wolff.

Donald Trump
(Matt Cardy/PA)

The letter demanded Mr Bannon “cease and desist” any further disclosure of confidential information.

The furore was was spurred by an unflattering new book by Mr Wolff that paints Mr Trump as a leader who does not understand the weight of the presidency and spends his evenings eating cheeseburgers in bed, watching television and talking on the phone to old friends.

Excerpts of Fire and Fury: Inside the Trump White House were published online by New York magazine and other media outlets ahead of the January 9 publication date.

The release left Mr Trump “furious” and “disgusted,” said White House Press Secretary Sarah Huckabee Sanders, who complained that the book contained “outrageous” and “completely false claims against the president, his administration and his family”.

In the book, Mr Bannon is quoted as describing a June 2016 meeting at Trump Tower between Donald Trump Junior, Trump campaign aides and a Russian lawyer as “treasonous” and “unpatriotic.”

Mr Bannon also speaks critically of president Trump’s daughter and White House adviser, Ivanka, calling her “dumb as a brick”.

“A little marketing savvy and has a look but as far as understanding actually how the world works and what politics is and what it means – nothing,” he is quoted saying.

New York magazine also published a lengthy adaptation of the book on Wednesday, in which Mr Wolff writes that Mr Trump believed his presidential nomination would boost his brand and deliver “untold opportunities” – but that he never expected to win.

It also claims Mr Trump Junior told a friend that his father looked as if he had seen a ghost when it became clear he might win the presidency. The younger Trump described Melania Trump as “in tears – and not of joy.”

The first lady’s spokeswoman, Stephanie Grisham, disputed that, saying Mrs Trump supported her husband’s decision to run, encouraged him to do so and was happy when he won.

“The book is clearly going to be sold in the bargain fiction section,” Ms Grisham said in a statement.

The book was based on more than 200 interviews, including conversations with the president and senior staff.