Biosecurity New Zealand (BNZ) is investigating after a suspected detection of Himalayan wineberry bramble in Auckland.
The plant is extremely invasive, and looks similar to a raspberry or blackberry bush.
Unitex scientists discovered the suspected weed growing near a park in Albany on Auckland's North Shore.
The plants can spread rapidly because they are difficult to control once established, and their seeds are spread by birds who eat the fruit.
Brendan Gould, Manager of Biosecurity Surveillance and Incursion for BNZ said a response is already underway.
"We have inspected the site to understand the situation and collect samples," he said.
"The samples are undergoing diagnostic testing to confirm if they are the Himalayan wine berry bramble.
"The suspected plants are well established, which suggests they have been present for some time, potentially many years.
"Once we get the test results we will consider what the next steps could be."