South Korean authorities are cracking down on the sale of a popular American pantry staple — Trader Joe's Everything but the Bagel seasoning — after forensic testing detected controlled narcotic substances in the product.

According to The Korea Herald, the Mapo Police Station in Seoul announced this week that it had identified listings for the seasoning blend on Karrot, a major South Korean secondhand marketplace platform. Police worked with the company to block all transactions involving the product.

The seasoning blend, which contains sesame seeds, garlic, onion, sea salt flakes, and poppy seeds, came under scrutiny after an analysis by South Korea's National Forensic Service detected morphine and codeine — both classified as controlled narcotic substances under South Korean law.

Authorities said some sellers brought the seasoning back from overseas trips before listing it for resale on the platform. Investigators believe some individuals attempted to sell or trade the product without realizing it contained prohibited substances.

Under South Korea's Narcotics Control Act, both buyers and sellers could face criminal charges for possessing or trading the seasoning. Travelers are also prohibited from bringing the product into the country. South Korea maintains some of the strictest narcotics enforcement among developed nations, with laws that criminalize possession and distribution of controlled substances regardless of whether the product was legally purchased abroad.

"Even if a product is legally sold overseas, it may be classified as a narcotic substance or a prohibited import in Korea, so particular caution is required," a police official told The Korea Herald.

"Consumers should check the relevant regulations before selling or purchasing food products brought in from abroad," police added. "We will respond strictly if products containing narcotic substances are found to be circulating."

Karrot agreed to restrict transactions involving the seasoning and has removed related listings since July 27.

South Korea first began restricting the seasoning in 2022 due to concerns over its poppy seed content. While poppy seeds themselves do not contain opium, they can become contaminated with opium alkaloids — including morphine and codeine — during the harvesting process, when the seeds may come into contact with the opium-containing fluid from the poppy plant. Other Asian jurisdictions, including Singapore, Taiwan, and the United Arab Emirates, have similarly restricted or banned food products containing poppy seeds over narcotics concerns.

In 2023, the U.S. Department of Defense advised American service members to avoid consuming foods containing poppy seeds, warning that doing so could result in a positive urinalysis for codeine.

FOX Business has reached out to Trader Joe's for comment.