President Donald Trump's personal lawyer, Michael Cohen, demanded Stormy Daniels "cease and desist" after the adult-film star said in a 60 Minutes TV interview that she was threatened with violence to stay silent about an alleged affair.
The actress - whose real name is Stephanie Clifford - was interviewed CBS yesterday. She is one of three women who have launched legal action over alleged affairs or sexual assault claims involving Mr Trump.
He strongly denies having had an affair with the actress.
His lawyers are seeking $US20m ($NZ27.4m) in damages from her, saying she broke a non-disclosure deal signed before the 2016 presidential election. She says the claim is invalid.
Ms Clifford said she had had sex with Mr Trump once in 2006, not long after he married Melania Trump.
"Mr Cohen had absolutely nothing whatsoever to do with any such person or incident, and does not even believe that any such person exists, or that such incident ever occurred," said the letter sent by Cohen's attorney, Brent Blakely, to the lawyer representing Daniels, Michael Avenatti.
Daniels had implied Mr Cohen was behind the threat of harm if she did not "leave Trump alone," which was made by a stranger in a Las Vegas parking lot in 2011.
The letter also demanded "that you immediately retract and apologize to Mr Cohen through the national media for your defamatory statements on 60 Minutes, and make clear that you have no facts or evidence whatsoever to support your allegations that my client had anything whatsoever to do with this alleged thug."
Daniels sued Trump on 6 March, saying he never signed an agreement for her to keep quiet about an "intimate" relationship between them.
White House aides did not respond immediately to requests for comment after the interview aired.
Mr Avenatti gave a number of television interviews yesterday.
He told NBC the man who threatened Daniels while she was with her infant daughter was not Cohen but that "it had to be someone that is related to Mr Trump or Mr Cohen."
Asked about the cease-and-desist letter on CNN, Mr Avenatti said Mr Cohen "needs to stop hiding behind pieces of paper and come clean with the American public".
Daniels' appearance followed an interview aired last week on CNN with former Playboy model Karen McDougal, who described a 10-month-long affair with Trump starting in 2006. Trump was married to his wife, Melania, during both alleged relationships.
The White House has said Trump denies having an affair with McDougal.
Mr Cohen said he paid Daniels $US130,000 of his own money during the 2016 presidential campaign, but has not explained why or if Trump was aware of the payment.
In filings with the Justice Department and Federal Election Commission watchdog groups have said the payment amount may have exceeded campaign-contribution limits and violated US law.
- Reuters / BBC