A number of poppy seed products have been recalled after a series of poisonings around the country.

Consumers are also being urged to check their pantries for seeds linked to the incidents after at least 12 people who developed unusual and severe symptoms and fell ill in NSW required urgent medical attention.

Additional cases have been reported across Australia.

The poppy seeds are not food grade, a joint investigation by state and territory governments has found.

"Ongoing investigations indicate the presence of unusually high levels of a naturally occurring chemical, thebaine, in the poppy seeds is likely causing this toxicity," NSW Health said in a statement on Tuesday.

Thebaine is found in poppy varieties and is used in the production of prescription medications including opiates.

Poppy seeds grown for food production generally have no detectable amounts of thebaine.

Symptoms of thebaine poisoning include spasms, seizures and difficulty breathing.

The products being recalled include Hoyt's Poppy Seeds and Gaganis Premium Australian Poppy Seeds, and new information gathered during the investigation means no amounts of the poppy seeds should be eaten.