WASHINGTON (NYTIMES, REUTERS) - US President Donald Trump's lawyer secretly obtained a temporary restraining order last week to prevent pornographic film star Stormy Daniels from speaking out about her alleged affair with Mr Trump, according to legal documents and interviews.

The order, issued by an arbitrator in California and reviewed by The New York Times, pertained to the actress whose real name is Stephanie Clifford, who had been paid US$130,000 (S$170,000) shortly before the 2016 election in what she calls a "hush agreement."

But in recent weeks, she had prepared to speak publicly about Mr Trump, claiming his lawyer, Michael D. Cohen, had broken the agreement.

The details of the order emerged on Wednesday (March 7) after the White House's spokeswoman, Sarah Huckabee Sanders, said that President Trump's lawyer had won an arbitration proceeding against Ms Clifford.

Ms Sanders's statement put the White House in the middle of a story that Mr Trump and his lawyer had been trying to keep quiet for well over a year.

The turn of events created the spectacle of a sitting president using legal maneuvers to avoid further scrutiny of salacious accusations of an affair and a payoff involving the porn star.

Ms Clifford has said she was taking legal action to be able to speak freely about the "intimate relationship" without fear of retribution.

According to the lawsuit, Ms Clifford and Mr Trump had an intimate relationship that began in the summer of 2006, not long after Mr Trump's wife Melania gave birth to their son Barron, and lasted well into 2007. The allegations could not be independently confirmed.

Ms Sanders denied Mr Trump had an affair with Ms Clifford and said arbitration over the legal case with the actress was won by the president's personal attorneys.

"The president has addressed these (allegations by Clifford) directly and made very well clear that none of these allegations are true," she said at Wednesday's White House press briefing.

"This case has already been won in arbitration and anything beyond that, I would refer you to the president's outside counsel."

A lawyer for the actress, Michael Avenatti, did not respond to a request for comment on Wednesday.

Ms Clifford's lawsuit said Trump lawyer Michael Cohen initiated a "bogus arbitration proceeding" against her on Feb 27, without notifying her, as part of efforts to "shut her up" and "protect Mr Trump".

Mr Cohen's lawyer Lawrence Rosen said in a statement on Wednesday that Mr Cohen obtained an order from an arbitrator prohibiting Ms Clifford from disclosing confidential information related to the nondisclosure agreement.

Mr Cohen has previously acknowledged he paid Ms Clifford US$130,000 in October out of his own pocket to not discuss her claims of an affair with Mr Trump.

Asked about the payment by Mr Cohen to Ms Clifford, Ms Sanders said she was not aware Mr Trump knew of it at the time.

Mr Cohen did not immediately respond to a request for comment. Trump attorneys John Dowd and Jay Sekulow were not immediately available for comment.