Trump claims his niece Mary 'is not allowed' to write her forthcoming book about him because of NDA

President says his relative signed ‘very powerful’ nondisclosure agreement as she prepares to release explosive book

Donald Trump has claimed his niece is “not allowed” to publish her upcoming new book about the president, citing a reported nondisclosure agreement she signed over 20 years ago after suing him and his siblings.

The president spoke out about Mary Trump’s forthcoming book, titled Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man, in an interview with Axios published on Sunday.

“She’s not allowed to write a book,” Mr Trump said about his niece. “You know, when we settled with her and her brother, who I do have a good relationship with — she’s got a brother, Fred, who I do have a good relationship with, but when we settled, she has a total ... signed a nondisclosure.”

The new book, which was scheduled for release in late July, was expected to detail how the president and his siblings allegedly used tax dodges and loopholes while securing $413m from their father’s business empire after his death. Ms Trump was also expected to our herself as a major source in the New York Times’ investigation about the president’s financial and tax controversies.

Ms Trump sued the president in 2000, arguing that he and his siblings cut off medical coverage to her nephew after he was born with a rare neurological disorder, despite their father having allocated funds in his estate to cover the family’s health insurance.

She slammed the president in an interview at the time, saying he and his siblings should have been “ashamed of themselves” while adding: “I’m sure they are not.”

Mr Trump claimed the nondisclosure agreement his niece signed was a “very powerful one” that “covers everything” and would effectively restrict her from publishing the upcoming work.

The president also alleged he and his family members were shocked to find out Ms Trump was set to release a book.

“I have a brother, Robert, very good guy, and he’s — he’s very angry about it,” he said. “But she signed a nondisclosure agreement and she’s obviously not honouring it if she writes a book. It’s too bad.”

According to Axios, the book will also reveal how Mr Trump allegedly “dismissed and derided” his father after he began falling ill due to Alzheimer’s. The president rejected those claims, claiming he “always had a great relationship” with his father.

He added: “That’s a disgraceful thing to say.”

The book was set for release just before the Republican National Convention. It has already topped the charts on Amazon, where it was available for pre-sale orders.