The man behind an explosive new book about life in the White House, is standing by the claims in it.

Michael Wolff's book Fire and Fury is being boosted by threats of legal action from American President, Donald Trump, who is painted in a poor light.

Michael Wollf said he had regular access to the West Wing and based his book on more than 200 interviews, including with President Trump himself.

He said there was one description that came up again and again in reference to the President.

"I will tell you the one description that everyone gave, everyone has in common, they all say he is like a child."

He said the overview from those he talked to was of a man both uneducated and reactionary.

"This man does not read, does not listen. He is like a pinball just shooting off the side."

White House spokeswoman Sarah Sanders is describing the book as a complete fantasy.

She said the White House rejected two dozen requests from Mr Wolff for an interview with Trump.