Donald Trump's lawyer says porn star defamed him

US President Donald Trump's personal lawyer, Michael Cohen, has 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 with Mr 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 Mr Cohen's attorney, Brent Blakely, to the lawyer representing Ms Daniels, Michael Avenatti, late on Sunday (local time), shortly after the interview aired on CBS. A copy of the letter was viewed by Reuters on Monday (local time).

Ms Daniels, whose real name is Stephanie Clifford, 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 apologise 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".

Ms Daniels sued Mr Trump on March 6, saying he never signed an agreement for her to keep quiet about an "intimate" relationship between them in 2006.

Ms Daniels attorney Mr Avenatti on Monday morning (local time) spoke with major news broadcasts.

In an interview with NBC, he said the man who threatened Ms Daniels while she was with her infant daughter was not Mr 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".

Ms Daniels' appearance followed an interview aired last week on CNN with former Playboy model Karen McDougal, who described a 10-month affair with Mr Trump starting in 2006. Mr Trump would have been married to his wife, Melania, during both alleged relationships.

The White House and Mr Cohen have both denied Mr Trump had an affair with Ms Daniels. The White House has said Mr Trump denies having an affair with Ms McDougal.

Mr Cohen said he paid Daniels US$130,000 of his own money during the 2016 presidential campaign, but has not explained why or if Mr Trump was aware of the payment.

Reuters