Journalist and best-selling author Michael Wolff has launched legal action against US first lady Melania Trump, accusing her of trying to silence him over the Epstein scandal.

The author of the Trump expose Fire and Fury lodged his counter-lawsuit in response to Melania suing him for $US1 billion ($A1.54 billion) in defamation damages over comments he made linking her to Jeffrey Epstein.

Melania Trump had demanded an apology for “false, defamatory, disparaging, misleading, and inflammatory statements” and monetary compensation for the alleged “overwhelming reputational and financial harm”.

“First Lady Melania Trump is proud to continue standing up to those who spread malicious and defamatory falsehoods as they desperately try to get undeserved attention and money from their unlawful conduct,” Nicholas Clemens, a spokesman for her, said.

The comments implying her association with Epstein were from podcasts hosted by Wolff, and an article by The Daily Beast.

The article was titled “Melania Trump ‘very involved’ in Epstein scandal: Author” with a sub-heading “The first lady has largely avoided the topic, but Trump biographer Michael Wolff suggests that she is acting behind the scenes”.

But Wolff has hit back with his own legal complaints, accusing the Trumps of making a practice of issuing costly legal threats to silence people.

“Mr Wolff is a journalist who has done his job diligently, reporting what he knows; identifying what he does not know; and asking important questions that deserve inquiry,” states the filing.

“In the face of the Threat Letter and its attack on his lawful reporting, Mr Wolff has no choice but to defend himself and to assert his rights.”

Wolff’s lawsuit came on the day that Trump’s lawyer had set as a deadline for him to retract statements, issue an apology and pay damages to his client.

The lawyer, Alejandro Brito, wrote on October 15 that Trump would be “left with no alternative” but to sue after the statements had caused her “overwhelming reputational and financial harm”.

Wolff’s 15-page filing alleges that his statements about Trump were true opinion and hypothesis, were made with no actual malice and were not defamatory.

Wolff alleges the Trumps are trying to promote a false statement that they had almost nothing to do with Epstein.

The suit notes that Wolff never said Melania Trump was involved in any of Epstein’s crimes.

Among the statements it said were true were that Melania Trump was “very involved” in Epstein’s social circle, where she met her future husband, and that Donald Trump liked to have sex with his friend’s wives and first slept with Melania on Epstein’s private jet.

The lawsuit said it was fair to question how Melania Trump fitted into the Epstein story.

And, it added, it was proper to “find out what happened in Mr Trump’s and Epstein’s 10 years of pursuing models, including supermodels, runway models, catalogue models, Eastern European models, and girls who just dreamed of being models”.

The Daily Beast reports that Wolff wants the court to allow him to question Melania and US President Donald Trump under oath about their dealings with Epstein.

“As a reporter, I’ve never had the opportunity to ask someone questions when their answers have to be given under an oath and in the presence of a court reporter,” he told The Daily Beast.

“I look forward to asking Melania and Donald Trump about the matters at issue in this case including their relationship with Jeffrey Epstein.”

Wolff is an award-winning journalist and author of 12 non-fiction books and biographies, including four about the Trump White House and Donald Trump’s 2024 campaign.

His lawsuit said he had contemplated writing a book about Epstein, and, in that effort, “has accrued many hours of recorded interviews of Jeffrey Epstein conducted over several years”.

Earlier this year, Donald Trump berated Wolff as a “Third Rate Reporter” and, in one lengthy social media post, called his upcoming book “a total FAKE JOB, just like the other JUNK he wrote”.

“His other books about me have been discredited, as this one will be also,” he said.

Wolff has regularly appeared in podcasts with The Daily Beast covering the Trump administrations including, among other things, the Epstein scandal and inquiry.