Eight protesters have been arrested on an oil drilling support vessel at Timaru's port.
Thirty protesters have been occupying the OMV support vessel at the port for more than 30 hours.
They are trying to stop the Skandi Atlantic from servicing the Austrian oil company's drill rig off the coast of Taranaki.
A police spokeswoman said they've been maintaining a presence at the scene to keep the peace.
But she said they've recently had to remove eight people from the boat - who'd moved into an unsafe area.