Photo: 123rf
The Ministry of Primary Industries has issued a warning against collecting shellfish from the Kaipara Harbour area.
MPI said routine tests on shellfish samples showed levels of paralytic shellfish poisoning toxins above the safe limit.
It said anyone eating shellfish from this area is at risk of illness - including mussels, oysters, pipi, cockles and scallops.
MPI said cooking the shellfish won't remove the toxins.
The warning extends throughout the entire Kaipara Harbour.
If anyone becomes ill after eating shellfish from an area where a public health warning has been issued, phone Healthline for advice on 0800 61 11 16, or seek medical attention immediately.
People are also advised to contact the nearest public health unit and keep any leftover shellfish in case it can be tested.