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

 Cynthia Ann Day and fiance Nathaniel Holmes.
Cynthia Ann Day and Nathaniel HolmesFacebook

Counterfeit alcohol had been eyed as a possible cause for three 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 fiancé 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 their deaths.

“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 them.

“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.