Singapore and South Korea have pulled Trader Joe's Everything But the Bagel seasoning from e-commerce platforms because it contains poppy seeds.

While they do not naturally contain opiates, poppy seeds are banned in both countries because they can get contaminated with opiates by fluid in the poppy plant during harvesting.

More than 20 online listings of the popular seasoning have been removed, Singapore's Central Narcotics Bureau said on Wednesday.

Last week, Seoul authorities said the seasoning tested positive for morphine and codeine, which are opiates found in the plant's sap.

Apart from poppy seeds, the product also contains sesame seeds, sea salt, minced garlic and minced onion. It was released by American grocery chain Trader Joe's in 2017.

Authorities in Singapore have urged anyone who has bottles of the seasoning to dispose of them.

"Singapore adopts a strict policy of zero tolerance towards controlled drugs," the narcotics bureau said, according to a CNA report.

"The possession, consumption, importation, exportation, manufacturing and trafficking of any controlled drug, even in trace amounts, is an offence under the Misuse of Drugs Act," it said.

In South Korea, investigators say some people brought the seasoning back home as souvenirs from their overseas trips before listing it for resale.

Some did so without realising it contained controlled substances, while others did so knowingly, according to a report by The Korea Herald.

"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 said.