This photo, provided on Friday by the National Intelligence Service, shows cannabis-infused food sold in Thailand.

Korean travelers have been advised to be careful about what they eat or drink overseas as they could consume cannabis-infused food unwittingly in countries where such products are legal.

In a warning issued Friday, the National Intelligence Service (NIS) said food options like a pork belly dish seasoned with cannabis salt or butter can easily be found in countries such as Thailand, one of the most popular holiday destinations for Koreans.

In many cases, products containing marijuana do not show ingredient information in Korean or English. As a result, foreign visitors purchase them inadvertently, violating the laws of their countries, according to the intelligence agency.

Even if they did so unknowingly, they could face legal troubles when they return to Korea. If they bring such products into Korea, a criminal investigation is inevitable.

If they are found to have consumed such products deliberately, they could face years behind bars.

"In Canada, ‘magic mushrooms,' categorized as an illegal substance in our country, are sold. In some Southeast Asian countries, drug-containing lollipops and many other types of illegal hallucinant chemicals have been traded," the NIS said.

Magic mushrooms, commonly known as "shrooms," are a type of mushroom that contain psilocybin and psilocin, substances that can cause hallucinations.

The spy agency also said that consuming such products increases the risk of becoming a target of criminals as they could be extorted or kidnapped while under the influence.

The use of marijuana has so far been legalized for recreational use in 24 U.S. states as well as Canada, Thailand, Germany, Malta, Luxembourg and South Africa among others.