A British tourist died of a suspected drowning in the pool of a luxe Spanish seafront villa owned by billionaire business magnate Sir Richard Branson’s sister, according to a new report.

Oliver Wissenbach, 25, of Coventry, was found dead in the pool of Villa Gloria — owned by artist Lindy Branson — around 7:45 a.m. Tuesday, The Sun reported. He was wearing swimming goggles when a maintenance worker discovered his body.

Officials believe that Wissenbach, who was renting the villa on the island of Menorca with his family, fell ill while taking a dip, according to the report. His family had just watched a nearby fireworks display the night before.

Authorities were probing the death in Mahon, the capital of the Balearic island in the Mediterranean Sea — but it was not believed to be suspicious.

“The police report has categorized this as an accidental death awaiting the result of an autopsy,” a source told The Sun. “Drowning is thought to be the cause. There was no ­evidence of violence or any kind of wrongdoing.”

Sir Richard — whose net worth is $4.1 billion — founded the Virgin Group in the 1970s, which now operates more than 400 companies in various fields.

Lindy Branson is a painter and sculptor, according to her website. Various royal family members have collected her work.

“As you can imagine, we were tremendously saddened by this tragic news,” she told The Sun of Wissenbach’s death. “Our thoughts and sympathies are with the family.”

Sir Richard and Lindy have a close relationship — and last year he posted a photo of the two celebrating her birthday with a drink in Menorca, according to the report.

A source told the outlet that “a lot of very wealthy people” visit Villa Gloria, which is “luxurious and popular with millionaires.”