Great Barrier Island has been included in a public health warning arising from the mysterious deaths of dogs and marine life in Auckland and the Hauraki Gulf.
Two dogs have died after visiting beaches on Auckland's North Shore over the past month, while deaths have also been reported of hundreds of fish, some penguins and five dolphins.
Auckland Regional Public Health Service tonight said it was unable to rule out the risk to the public for the Hauraki Gulf and Great Barrier Island, 90km from downtown Auckland, until test results were received.
In the meantime, people in the area should avoid contact with seawater and sea life.
They should also avoid taking children to beaches or exercising pets there.
The service also advised against collecting or eating fish and shellfish from the area, and urged that fishing, swimming and diving activity should cease.
It said it was continuing to work with local and regional councils and government agencies to try to establish the cause of the deaths.
A North Shore City Council spokeswoman said results of tests in relation to the dog that died after visiting Cheltenham Beach this week were expected next week.