Kensington Palace would not comment further.
It was the subject of fevered speculation among royal watchers on Monday night after Prince Harry and Meghan Markle asked for "understanding" amid claims that Thomas Markle, Meghan's father, won't be attending the royal wedding.
Thomas Markle told TMZ he's experiencing serious chest pains after his heart attack six days ago.
Prince Harry will marry Meghan Markle on May 19, 2018.
Samantha Markle, Markle's daughter by his first marriage, has publicly demeaned her half-sister as a social climber who doesn't care about her family back in in the United States.
"I like to think he was drawn to her sweet eyes and her Afro, plus their shared love of antiques", wrote Meghan in an essay for ELLE UK on being mixed race.
In fact, he won't be going to the wedding at all, telling TMZ him that he recently suffered a heart attack. "They rented the house next to him in Mexico, four or five of them, he can't open his blinds, he can't go anywhere without being followed", she said.
None of them were invited to the wedding.
Speaking on the red carpet for a screening of her latest project, King Lear, she really didn't have much to say about the whole thing.
His participation in the highly anticipated event had remained a mystery until last week when the Kensington Palace confirmed that he was indeed attending his daughter's wedding at St George Chapel at Windsor Castle.
According to reports, he stopped for a few hours' sleep and then carried onto LA where he was photographed putting a pot of flowers on the doorstep of his ex-wife, Doria Ragland - Miss Markle's mother.
Ex-Suits actress Ms Markle's father is a former lighting director who worked on programmes including the 80s TV show Married with Children and General Hospital, for which he and his team won two Emmy awards.