Donald Trump

Filed in Miami, the lawsuit features arguments that will likely appear in Mr Trump’s defence to charges that he falsified internal business records to disguise payments made to the porn actress Stormy Daniels during his presidential campaign in 2016.

Mr Cohen is accused in the suit of falling foul of a confidentiality agreement that he had signed as a condition of his employment.

Lanny Davis, his spokesman, said the case would not stop Cohen from co-operating with prosecutors.

He said: “Trump appears once again to be using and abusing the judicial system as a form of harassment and intimidation against Michael Cohen. It appears he is terrified by his looming legal perils and is attempting to send a message to other potential witnesses who are co-operating with prosecutors against him.”

He predicted the action would fail and asked: “Is there anyone in America, aside from a shrinking minority base of believers, who takes Mr Trump seriously when he files these apparently frivolous lawsuits?”