A new book has claimed that Donald Trump's daughter Tiffany Trump, and daughter-in-law Vanessa Haydon Trump, were reportedly "inappropriately - and perhaps dangerously- close" to secret service agents who protected the family while Trump was in power as the President of the United States.

Pulitzer Prize-winning Washington Post reporter Carol Leonnig made the claims in her new book "Zero Fail: The Rise and Fall of the Secret Service," which is scheduled to hit the shelves on May 18. Leonnig, who is also the co-author of "A Very Stable Genius: Donald J. Trump's Testing of America," has described her latest work as "the first definitive account of the rise and fall of the Secret Service, from the Kennedy assassination to the alarming mismanagement of the Obama and Trump years, right up to the insurrection at the Capitol on January 6."

Excerpts from the book shared by The Guardian claim that Vanessa Trump, who was married to the former POTUS's oldest son Donald Trump Jr, "started dating one of the agents who had been assigned to her family." The former model filed for an "uncontested divorce" from Donald Jr. in 2018 after 13 years of marriage.

The book further claims that Tiffany Trump, Donald Trump's younger daughter whom he shares with ex-wife Marla Maples, also broke up with a boyfriend and "began spending an unusual amount of time alone with a Secret Service agent on her detail." Leonnig writes that agency officials had become "concerned at how close Tiffany appeared to be getting to the tall, dark and handsome agent," and reassigned him, even though both he and the first daughter insisted there was no inappropriate relationship between them.

Tiffany, who announced her engagement to partner Michael Boulos on her father's final full day in the White House in January this year, has denied the claims made about her in the book. A spokesperson for the 27-year-old told The Washington Post that her "experience with the Secret Service was entirely professional" and claims otherwise were "nothing more than gossip."

Meanwhile, a Secret Service spokesperson said in its defense: "The U.S. Secret Service is aware of an upcoming book which re-hashes past challenges the agency overcame and evolved from. Now and throughout its 156-year history, the agency's skilled workforce is dedicated to the successful execution of its critical protective and investigative missions."

Trump family
(L-R) Eric Trump, Lara Yunaska Trump, Donald Trump, Barron Trump, Melania Trump, Vanessa Haydon Trump, Kai Madison Trump, Donald Trump Jr., Donald John Trump III, Jared Kushner, Ivanka Trump, and Tiffany Trump pose for photos on stage after Donald Trump announced his candidacy for the U.S. presidency at Trump Tower on June 16, 2015 in New York City. Getty Images