An FBI investigation has ruled out tainted booze as the cause in three mysterious US tourist deaths in the Dominican Republic, according to a report.

Counterfeit alcohol had been eyed as a possible cause in a trio of fatalities on the island, including a Maryland couple who died in the same hotel room in May at the Grand Bahia Príncipe resort, The Hill reported.

Nathaniel Edward Holmes, 63, and his fiancée, Cynthia Day, 49, were both found dead of respiratory failure and pulmonary edema the day they were supposed to check out in La Romana, local authorities said at the time.

But US officials said bad booze wasn’t to blame in the couple’s deaths or in the death of a third person, who wasn’t identified.

“The results of the additional, extensive toxicology testing completed to date have been consistent with the findings of local authorities,” a State Department spokesperson told The Hill. “Methanol poisoning from tainted alcohol was ruled out by the FBI in these cases during the toxicology screening, and it was not the finding in any other cases of U.S. citizen deaths investigated by Dominican authorities.”

The investigation was launched in the wake of a series of tourist deaths on the island, including some who drank from the hotel minibar before becoming fatally ill.

Law enforcement sources told The Post back in June that the agency was looking into who supplied the alcoholic beverages — and whether the booze had dangerous chemicals in it.

“Toxicology test results to date have been provided by the FBI to Dominican authorities, and family members of the deceased have been informed,” the State Department spokesperson told The Hill.