A health warning has been issued after extremely high levels of paralytic shellfish toxins were detected in routine samples taken from Port Levy on Banks Peninsula.

The warning covers coastal areas from New Brighton to the northern side of Hickory Bay.

Health New Zealand said people should avoid the area and keep animals away from the water until the warning is lifted.

Public Health Medicine Specialist Dr Imogen Evans said the algal bloom could produce toxins harmful to both humans and animals.

“People should avoid contact with the water until further notice.”

“The bloom appears to be limited to Port Levy, but people should still take care in nearby bays as toxins could travel to other areas.”

Evans said exposure could cause a range of symptoms including skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips.

“If you experience any of these symptoms, visit your doctor immediately and please let them know if you have had contact with the water.”

New Zealand Food Safety also issued a public health warning advising people not to collect or eat shellfish gathered from the northern side of Banks Peninsula.

Officials said anyone who becomes ill after eating shellfish from an affected area should call Healthline on 0800 61 11 16 or seek medical attention immediately.

People are also being asked to contact their nearest public health service and keep any leftover shellfish so it can be tested if required.