Trump's former doctor Harold Bornstein has said he did not write a glowing letter in December 2015 declaring the then-Republican presidential candidate's "astonishingly excellent" health.
For long, United States President Donald Trump has criticised the media for publishing "fake news" about him.
Now it has emerged that he may have faked his own bill of health in 2015, ahead of the presidential election.
Trump's former doctor Harold Bornstein has said he did not write a glowing letter in December 2015 declaring the then-Republican presidential candidate's "astonishingly excellent" health, according to a US media report.
"He dictated that whole letter. I didn't write that letter," Bornstein told CNN about 71-year-old Trump, who became the oldest president to be elected in US history.
"I just made it up as I went along," Bornstein, a gastroenterologist, best known as Trump's personal physician for more than three decades, told the network.
"His (Trump's) physical strength and stamina are extraordinary," he had crowed in the letter, which was released by Trump's campaign in December 2015.
"If elected, Mr. Trump, I can state unequivocally, will be the healthiest individual ever elected to the presidency," Bornstein had said.
The missive did not offer much medical evidence for those claims beyond citing a blood pressure of 110/65, described by Bornstein as "astonishingly excellent."
It claimed that Trump had lost 15 pounds over the preceding year. And it described his cardiovascular health as "excellent."
"That's black humour, that letter. That's my sense of humor," he said. "It's like the movie 'Fargo': It takes the truth and moves it in a different direction."
He said Trump read out the language as Bornstein and his wife were driving across Central Park.
"(Trump) dictated the letter and I would tell him what he couldn't put in there," he said. "They came to pick up their letter at 4 o'clock or something."
The White House did not respond to a request for comment about Bornstein's claim, CNN said.
It is not clear why Bornstein is making these allegations now.
The admission is an about face from his answer more than two years when the letter was released and answers one of the lingering questions about the last presidential election, CNN commented.
A few weeks ahead of its release, Trump had tweeted that Bornstein's medical report would show "perfection".
"I am fortunate to have been blessed with great genes," Trump wrote on Facebook at the time.
In January this year Trump had a three-hour examination amid speculation over his mental health.
Meanwhile, Bornstein also said that Trump's ex-bodyguard Keith Schiller had carried out a "raid" on his offices in February 2017, removing all of Trump's medical records.
The incident happened two days after Bornstein told a newspaper that he had for years prescribed Propecia, a hair growth medicine, for Trump.
Bornstein told NBC News that he was not given a form authorising him to release Trump's records, and that Schiller, along with Trump Organisation lawyer Alan Garten, took the originals and copies of Trump's charts and lab reports, including records filed under pseudonyms.
The raid left him "raped, frightened and sad", Bornstein said.
But White House press secretary Sarah Sanders later insisted that the incident was not a raid and that it was "standard procedure" for the White House Medical Unit to take possession of the president's medical records.
Trump has been highly critical of some of the US media outlets for not toeing his line.
He also instituted The Fake News Awards this year to point out the news outlets he said were responsible for misrepresenting him or producing false reports both before, and during, his presidency.