LONDON

Meghan Markle’s half sister said today that their retired father is under an “unbelievable” amount of stress because of relentless pressure from reporters and paparazzi hounding him at his home in Mexico.

Samantha Markle told the “Good Morning Britain” TV show that Thomas Markle recently panicked while driving on the highway because he was being followed by numerous press cars, what she called a “dangerous situation.” She said reporters had also harassed him at his home and that he recently suffered a heart attack.

Thomas Markle, a retired cinematographer who worked in Hollywood for many years, is in his mid-70s. He is divorced from Meghan Markle’s mother, Doria Ragland.

“He was so stressed out. 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. “Really, it’s quite atrocious and intrusive and I think it’s highly unethical.”

She gave no dates for when any of those events took place.

There are now doubts about whether Thomas Markle plans to attend Saturday’s royal wedding between his daughter and Prince Harry. He had been expected to walk Meghan Markle down the aisle at St. George’s Chapel on the grounds of Windsor Castle. But he reportedly told the celebrity website TMZ that he is no longer planning to come to the wedding where 600 guests have been invited.

It was not immediately possible to reach Thomas Markle for comment and it’s not clear if he may change his plans again in the next few days.

Prince Harry and Meghan Markle on Monday night issued a statement asking for “understanding and respect” for Thomas Markle.

In the days before the wedding, both of Meghan Markle’s parents had been expected to meet with Queen Elizabeth II — Harry’s grandmother.