Donald Trump’s former doctor has said that the US president himself dictated an infamous letter describing his own “extraordinary” physical health and stamina.

Dr Harold Bornstein admitted he did not write the December 2015 letter, attributed to him, in which the then-presidential candidate’s physical condition was hailed in sometimes hyperbolic language.

The letter said: “If elected, Mr Trump, I can state unequivocally, will be the healthiest individual ever elected to the presidency.”

Dr Bornstein’s statement also claimed that Mr Trump’s blood pressure was “astonishingly excellent”, while his cardiovascular health was also “excellent”.

Now, in an interview with CNN, the president’s former personal physician said: “He dictated that whole letter. I didn’t write that letter.

“I just made it up as I went along.”

In September 2016, Dr Bornstein offered a more sedate assessment of the president’s health, claiming that he had been “rushed for time” when he wrote the original letter, but insisting that the words were his own.

Now, Dr Bornstein tells CNN: “That’s black humour, that letter. It’s like the movie Fargo. It takes the truth and moves it in a different direction.”

Dr Bornstein added that Mr Trump “dictated the letter, and I would tell him what he couldn’t put in there” as he and his wife drove across Central Park in New York City, adding: “They came to pick up their letter at four o’clock or something.”