President Donald Trump's doctor, in an extraordinary official statement issued at the behest of the president Tuesday, said that Trump has not experienced or been evaluated for a stroke, mini-stroke or heart-related emergencies.
The statement came hours after Trump claimed on Twitter that unnamed people are "trying to say that your favorite President, me, went to Walter Reed Medical Center, having suffered a series of mini-strokes."
"Never happened to THIS candidate - FAKE NEWS," Trump wrote in a tweet.
Trump's tweet in turn, came shortly after FoxNews.com, the online sister of Fox News, published an article noting that Joe Lockhart, who had served as White House press secretary under President Bill Clinton, on Monday tweeted, "Did @realDonaldTrump have a stroke which he is hiding from the American public?"
The president is an avid watcher of Fox News.
NBC News' White House correspondent Peter Alexander reported Tuesday that Trump was responding to Lockhart's tweet.
Dr. Sean Conley, the president's physician, in his statement said that Trump "has asked that I ... address the recent public comments regarding his health."
"I can confirm that President Trump has not experienced nor been evaluated for a cerebrovascular accident (stroke), transient ischemic attack (mini stroke), or any acute cardiovascular emergencies, as have been incorrectly reported in the media," Conley said.
"The President remains healthy and I have no concerns about his ability to maintain the rigorous schedule ahead of him," Conley said.
"As stated in my last report, I expect him to remain fit to execute the duties of the Presidency," he added
The White House did not immediately respond to CNBC when asked what media outlets or reporters had claimed he may hay suffered a stroke, mini-stroke or heart attack.
But in recent days, there has been speculation on Twitter, by Lockhart' and others, that the president may have had a stroke at the time he made a visit to Walter Reed National Military Medical Center last November.
That visit was not previously announced on his official schedule.
Lockhart's tweet came on the heels of a report by CNN about a forthcoming book by New York Times reporter Michael Schmidt, which discusses the Walter Reed visit.
Schmidt wrote that he had learned "in the hours leading up to Trump's trip to the hospital, word went out in the West Wing for the vice president [Mike Pence] to be on standby to take over the powers of the presidency temporarily if Trump had to undergo a procedure that would have required him to be anesthetized."
After Lockhart posted his tweet speculating on the question of whether Trump had had a stroke, Dr. Ronny Jackson, a former White House physician for Trump, replied to it in what Lockhart said was an attack.
Jackson, who is running for a seat in Congress representing a Texas district, later deleted the reply, Lockhart said.
Jackson "basically said that this was all fake news and he could attest to the President being in great health," Lockhart told CNBC.
"Not sure how he could do that since he wasn't the doc at the time of the Walter Reed visit," Lockhart added.
Trump's reelection campaign later called for CNN to fire Lockhart as a political analyst for "knowingly pushing a conspiracy theory about President Trump's health."
"If another CNN employee said similar things about Barack Obama they'd be fired immediately, so the same standard should be applied here," the campaign said in a prepared statement. "That is, of course, unless CNN is complicit in the smear campaign in order to level the playing field against Joe Biden, somebody who truly has lost a step."
-- Additional reporting by CNBC's Christina Wilkie.