A sixth American tourist was reported Monday to have died from a mysterious illness at a Dominican Republic resort — the latest in a string of disturbingly similar fatalities.

Many of the deaths — and several other severe illnesses — involve healthy, middle-aged adults who had taken a drink from their hotel room minibar before suddenly becoming gravely sick.

That connection seems like more than a coincidence to the victims’ loved ones — and has led to new calls for action and even for the FBI to step in and investigate.

The latest death to be revealed was that of Robert Bell Wallace, 67, of California, who officials said died on April 14 during a stay at the Hard Rock Hotel & Casino in the Dominican resort town of Punta Cana.

Wallace’s cause of death has yet to be determined. But his niece told Fox News that her uncle became unwell shortly after drinking a glass of scotch from the minibar in his room before dying in a hospital three days later.

“We have so many questions,” niece Chloe Arnold told Fox. “We don’t want this to happen to anyone else.”

Compounding the mystery is the fact that another American tourist, David Harrison, 45, of Maryland, had died at the same Hard Rock in July 2018 under similarly strange circumstances.

And just one month after Wallace died, three others mysteriously died in their rooms at another Dominican resort in a five-day period this May.

Miranda Schaup-Werner, 41, of Pennsylvania, collapsed and died in her room on May 25 after having a drink from her minibar at the Luxury Bahia Principe Bouganville in La Romana, 70 miles west of Punta Cana.

Five days later, Edward Holmes, 63, and Cynthia Day, 49, were found dead in their room at the neighboring Grand Bahia Principe resort.

The sister of Philadelphia woman Yvette Monique Short, 51, last week called for answers after her sister died suddenly while staying at the Bahia Principe last June. Felicia Nieves told WTXF her sister had a drink from the minibar inside her room, went to bed and never woke up.

The deaths made headlines and first put the spotlight on what now appears to be a yearlong pattern.

The reports of the growing death toll were particularly disturbing to Brooklyn’s Awilda Montes, 43, who said she began vomiting blood after drinking soda from her minibar at the Grand Bahia Principe last October — but managed to survive.

“This could have been me in the headlines,” Montes told The Post. “If I knew then what I know now, I would have left the island straightaway.”

Montes suspects someone replaced the soda with chlorine and says she has been left with no taste buds, permanent respiratory problems and ongoing anxiety.

“I’ve heard all these different theories and the most that make sense to me would be a disgruntled employee or a serial killer,” she said. “I’m doing preparations for my daughter’s baby shower and yesterday she turned to me and said, ‘Just to think you could be gone, you could have missed all of this.’ ”

It wasn’t clear if Holmes and Day drank from the minibar, and their deaths were attributed by officials to respiratory failure. As for Schaup-Werner, Dominican officials said she had a heart attack, but her brother-in-law, Jay McDonald, insisted she died of respiratory failure and had drunk from the bar.

The Bahia resorts are both run by Bahia Principe Hotels & Resorts, a Spanish family-owned hotel chain. In a statement on its website, Grupo Pinero — the company that operates the resorts — was unapologetic, accusing the media of spreading “inaccurate and false information” and of causing their reputation to suffer “great damage.”

A team of experts from the US Centers for Disease Control and Prevention and the World Health Organization has since descended on the hotels and is conducting tests at the Bahia Principe hotels where the trio died.

Harrison’s widow, Dawn McCoy, said she was told her husband’s death last July at the Hard Rock was a heart attack, but says she now doubts that determination.

McCoy said her husband was mumbling, sweating profusely and “had a very potent, strange smell” before his death.

“I accepted it,” McCoy told the Washington Post on Saturday. “Then, when all these people started passing, I stopped and thought to myself, ‘How can all these people have the same cause of death as David?’ ”

Colorado couple Kaylynn Knull, 29, and Tom Schwander, 33, filed a lawsuit against the hotel’s owners earlier this year after a doctor ruled they had suffered insecticide poisoning while vacationing at the Grand Bahia Principe Hotel La Romana last June.

The pair told CNN on Friday they became seriously ill after noticing an overpowering “chemical smell” in their room.

At a press conference Thursday, Dominican Republic Tourism Minister Francisco Garcia insisted the island was safe as more tourists reportedly are canceling their vacation plans. Garcia said the country had received more than 30 million visitors in the last five years without any widespread concerns about health issues at its resorts.