The Canadian Food Inspection Agency is recalling certain varieties of Pacific oysters harvested earlier this week in B.C.

The agency says the oysters may be unsafe due to the presence of a marine biotoxin that can cause paralytic shellfish poisoning when eaten.

The recall applies to farm-raised oysters harvested on July 14 under the brand name Union Bay Seafood Ltd., which is based in Richmond, B.C.

The affected products include:

Pacific oysters, Mica's Petite Effingham Inlet (five-dozen packs)

Pacific oysters, Effingham Inlet Xs (five-dozen packs)

Oyster N/Shell Effingham XSM (five-dozen packs)

The oysters are distributed in B.C., Alberta and Ontario.

Symptoms can appear within a few minutes or up to 10 hours after consumption. They include tingling and numbness of the lips, tongue, hands and feet, and difficulty swallowing.

Severe symptoms include difficulty walking, muscle paralysis, respiratory paralysis and death.

The agency says the recall was triggered by test results and no illnesses have been reported. It says recalled products should be thrown out or returned to the store where they were purchased.