Donald Trump has responded to viral online rumours about his death, saying he was unaware the false reports were taking off on social media while he was out of the public spotlight in recent days.
"I didn't hear that one," the US president said after a reporter raised the issue at a White House press conference.
"That's pretty serious."
In another example of a false conspiracy rapidly spreading on social media — assisted by algorithms that reward hysteria over accuracy — hashtags such as #trumpdead and #whereistrump began trending over America's Labor Day long weekend.
The unfounded theories that Mr Trump had died were fuelled by his week-long break from public engagements and recent images of his bruised hands and swollen ankles.
Some posts speculating about his health were rewarded with more than a million views.
Illinois Governor JB Pritzker even responded to a critical post from Mr Trump by saying: "Why don't you send everyone proof of life first?" His post was retweeted more than 6,000 times.
Mr Trump used his own platform, Truth Social, to insist he had "NEVER FELT BETTER IN MY LIFE" on Sunday evening, local time.
On Tuesday, he said he knew people had been speculating about his health.
But after a Fox News reporter asked him: "How did you find out over the weekend that you were dead?" Mr Trump said he "didn't hear it to that extent".
"I have heard. It's sort of crazy, but last week I did numerous news conferences, all successful," Mr Trump said.
"And then I didn't do any for two days and they said, 'There must be something wrong with him.'
"[Former US president Joe] Biden wouldn't do them for months, you wouldn't see him, and nobody ever said there was ever anything wrong with him."
Mr Trump held the press conference to announce a plan to move the headquarters for the US's outer-space military force, Space Command, from Colorado to Alabama. He was not asked any further questions about his health.
In July, the White House said he had been diagnosed with chronic venous insufficiency (CVI), a condition where weakened veins in a person's legs are unable to effectively pump blood back to the heart.
The condition is not considered a serious health threat, but can cause pain, swelling, skin changes and varicose veins.
