Dominican Republic officials are reportedly investigating the potential use of bootleg alcohol in the Dominican Republic amid several US tourist deaths in the country – here’s what that is.

Unregulated alcohol, also known as counterfeit or bootleg alcohol, is an international problem, having caused deaths in India, Iran, Indonesia, and several other countries in recent years.

Such beverages are largely produced illegally and driven by the economic benefit of it being far cheaper to produce than legal, branded products, according to the International Alliance for Responsible Drinking (IARD).

Now police are reportedly looking into whether several US tourists who died while staying at all-inclusive resorts were poisoned by bootleg alcohol in the Dominican Republic, law enforcement sources told the New York Post.

INSIDER has contacted the Dominican Republic National Police for comment on the report.

Alcohol sold outside governmental regulation is untaxed, and avoids quality and health regulations, which can lead do it being toxic or deadly.

Illicit alcohol is widespread across Asia, parts of Europe, Africa and Latin America, the IARD said.

According to nonprofit alcohol awareness group Safeproof.org, some counterfeit alcohol is produced in a hurry to "make easy money."

To speed up the process, some producers might cut distillation processes short by mixing water with indigestible alcohol compounds, like methanol, instead of the traditional ethanol.

Read more: Dominican Republic officials are reportedly investigating whether recent tourist deaths were caused by counterfeit alcohol

Cultural and economic factors also come into play with unregulated alcohol - its largely produced in poorer areas, the IARD said, and in areas where there are severe restrictions around licensing hours and sales of liquor.

According to the Journal-Sentinel, there are several ways to tell if alcohol is counterfeit. The paper detailed signs of bootlegged alcohol after the US State Department issued a warning about tainted alcohol at Mexican resorts last year.

The paper said people should look at bottles' caps, labels, inks and glues when investigating if a bottle is authentic.

Caps should not leak or rotate, holograms should be consistent with other bottles, authentic bottles will likely use horizontal glue on its labels, and labels should not be places on top of other lanes.

Additionally, bottles should not be cloudy or have falling particles in the liquid.

Unregulated alcohol includes beverages produced outside government regulations, alcohol with original branding that has been illegally imported, branded alcohol that has been fraudulently tampered with, legally produced alcohol that was not taxed, beverages produced with denatured alcohol, and alcohol products not meant for human consumption that is consumed by humans, according to the IARD.

According to the World Health Organization informally and illegally produced alcohol accounted for a quarter of all alcohol consumed in 2014 globally.