New York judge refused on Thursday to block a "tell-all" book by President Donald Trump's niece that brands him "the world's most dangerous man."

Mary Trump's purportedly explosive book is scheduled to appear at the end of July, just three months before her uncle Donald stands for reelection.

Early this week, the president's brother Robert Trump asked a court in Queens, New York to issue a temporary restraining order to prevent the publication of "Too Much and Never Enough," that is subtitled: "How My Family Created the World's Most Dangerous Man."

Echoing comments by the president, Robert Trump accused Mary of violating a non-disclosure agreement she signed in 2001 after the same court settled a contentious fight over the estate of real estate tycoon Fred Trump -- the father of Donald and Robert and of Mary's father Fred Trump Jr, who died in 1981.

In the 240-page book, Mary, 55, recounts what she witnessed of the "toxic family" in the home of her grandparents, according to publish Simon and Schuster.

"She describes a nightmare of traumas, destructive relationships, and a tragic combination of neglect and abuse," the publisher said.

A clinical psychologist, Mary Trump "is the only Trump willing to tell the truth about one of the world's most powerful and dysfunctional families," it said.

US President Donald Trump
US President Donald Trump's niece is set to release a no-holds-barred memoir titled "Too Much and Never Enough: How My Family Created the World's Most Dangerous Man". Photo: AFP / SAUL LOEB

The Daily Beast reported earlier this month that the book will reveal that Mary Trump was the crucial source for explosive New York times reporting on Trump's finances, suggesting the billionaire paid little in tax for decades.

President Trump last week told Axios that Mary Trump's non-disclosure agreement prevents her from revealing family secrets.

"She's not allowed to write a book," he said.

"You know, when we settled with her and her brother... she ... signed a nondisclosure."

But the judge in the case said his court, the Queens Country Surrogate Court, was not the right jurisdiction to seek an injunction against the book.

Mary Trump's lawyer Ted Boutrous said in a statement that he hoped that would be the end of the matter.

"Democracy thrives on the free exchange of ideas, and neither this court nor any other has the authority to violate the (US) Constitution by imposing a prior restraint on core political speech," he said.

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