Washington (CNN) President Donald Trump has stepped up attacks against a new book by Michael Wolff about his campaign and the early days of his presidency, calling it "full of lies."

Trump, in a Thursday night tweet, implored people to look at Wolff's past and referred to his former-adviser-turned-latest-target, Steve Bannon, as "Sloppy Steve."

"I authorized Zero access to White House (actually turned him down many times) for author of phony book! I never spoke to him for book. 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 President tweeted.

The White House has been taking issue with claims from the book, "Fire and Fury," since adapted excerpts of it began to surface online ahead of its publication. Quotes attributed to Bannon that were negative about Trump and son Donald Trump Jr. led to a scathing statement from Trump, in which the President said his former campaign executive and top aide had "lost his mind."

The White House has likewise attacked the book, with press secretary Sarah Sanders calling it "complete fantasy," and an attorney for Trump sent a legal threat to the book's author and publisher.

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