At approximately 7.15am Police in New Plymouth received a report that protestors representing Greenpeace were boarding a ship docked in Port Taranaki.
It is understood that there are five or six protestors aboard the Noble Discoverer who have scaled a drilling tower and are displaying banners.
Area Commander for New Plymouth Police, Inspector Blair Telford, said: "Our role in these situations is to ensure any protest is lawful and the owners and crew of the ship are allowed to go about their lawful business. The protestors are clearly breaking the law by trespassing on the ship and we are currently liaising with the Port of Taranaki and the Harbour Master to decide the most appropriate course of action. Public safety is paramount."
The port has been temporarily closed.