First Lady Melania Trump has threatened to sue Hunter Biden for more than $1bn after he claimed she was introduced to her husband by sex offender Jeffrey Epstein.

Lawyers acting on behalf of the first lady, who married US President Donald Trump in 2005, described the claim as "false, disparaging, defamatory and inflammatory".

Biden, son of former US President Joe Biden, made the comments during an interview earlier this month, in which he strongly criticised the president's former ties to Epstein.

Donald Trump was a friend of Epstein, but has said the pair fell out in the early 2000s because the financier had poached employees who worked at the spa in Trump's Florida golf club.

A letter from the first lady's lawyers and addressed to an attorney for Hunter Biden demands he retract the claim and apologise, or face legal action for "over $1bn in damages".

It says the first lady has suffered "overwhelming financial and reputational harm" because of the claim he repeated.

It also accuses the youngest Biden son of having a "vast history of trading on the names of others", and repeating the claim "to draw attention to yourself".

During a wide-ranging interview with filmmaker Andrew Callaghan published earlier this month, Hunter Biden claimed unreleased documents relating to Epstein would "implicate" President Trump.

He said, "Epstein introduced Melania to Trump - the connections are so wide and deep." The first lady's legal letter notes that the claim was partially attributed to Michael Wolff, a journalist who authored a critical biography of the president.

In a recent interview with US outlet The Daily Beast, Wolff reportedly claimed that the first lady was known to an associate of Epstein and Trump when she met her now-husband.

The outlet later retracted the story after receiving a letter from the first lady's attorney that challenged the contents and framing of the story.

There is no evidence that the pair were introduced to each other by Epstein, who took his own life in prison while awaiting trial in 2019.

In the first lady's legal letter, Hunter Biden is accused of relying on a since-removed article as the basis of his claims, which it describes as "false and defamatory".

A message on the archived version of the Daily Beast online story reads: "After this story was published, The Beast received a letter from First Lady Melania Trump's attorney challenging the headline and framing of the article.

"After reviewing the matter, the Beast has taken down the article and apologises for any confusion or misunderstanding."

Asked about the legal threat, the first lady's lawyer, Alejandro Brito, referred BBC News to a statement issued by her aide, Nick Clemens.

It read: "First Lady Melania Trump's attorneys are actively ensuring immediate retractions and apologies by those who spread malicious, defamatory falsehoods."

A January 2016 profile by Harper's Bazaar reported the first lady met her husband in November 1998, at a party hosted by the founder of a modelling agency.

Melania Trump, 55, told the publication she declined to give him her phone number because he was "with a date".

The profile said Trump had recently separated from his second wife, Marla Maples, whom he divorced in 1999. He was previously married to Ivana Trump between 1977 and 1990.

The BBC has contacted Hunter Biden's attorney.

The legal letter comes after weeks of pressure on the White House to release the so-called Epstein files, previously undisclosed documents relating to the criminal investigation against the convicted paedophile.

Before being re-elected, Trump said he would release the records if he returned to office, but the FBI and Justice Department said in July that no "incriminating" client list of Epstein associates existed.