A peaceful protest aboard an oil drilling company's ship in Timaru has already brought out the authorities.

Around 30 protesters stormed the support vessel, which was preparing to travel to the OMV-commissioned oil rig off the Taranaki coast.

Some locked themselves to the ship in an attempt to stop it from departing.

Greenpeace campaigner Amanda Larsson says Police showed up not long after they boarded the vessel.

"This came as a bit of a surprise as you can imagine so they're just doing their job as police and security this morning, and we'll be following that throughout the day to see what happens."

Here's the view from onboard @OMV's oil rig support vessel in Timaru. 30 community activists are still on the ship. By occupying @OMV’s henchboat, we’re delaying their monster oil rig from drilling for new oil in the middle of a climate emergency. #PeoplevsOil #ClimateUprising pic.twitter.com/AJ6E6sPaTu

— Greenpeace NZ (@GreenpeaceNZ) November 23, 2019

She says that they can't protest the rig directly, so they're stopping its chain of support.

"This support vessel is needed by OMV in order to be able to set its an anchors and start drilling. So the intention today is to stop that from happening, and that means this group of people is prepared to stay there for as long as it takes."

The protesters have draped a bright pink banner across the ship.

According to RNZ, OMV is preparing to begin drilling three oil wells there.

Larson says that other protest groups, including Extinction Rebellion, are involved in the protest.