About 30 environmental protesters have stormed an Austrian oil company's support ship in Timaru to prevent it leaving port.
The Bahamas-flagged OMV was preparing to leave the Port of Timaru and travel north to the oil rig off the coast of Taranaki.
Greenpeace said OMV is about to begin drilling three oil wells there.
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
Police said they were called to the port at about 6am.
They said officers are on site to ensure safety and to uphold the law while recognising the lawful right to protest.
Climate and energy campaigner Amanda Larsson said those taking part in the occupation are prepared to stay overnight.
"By occupying OMV's henchboat, we're delaying the monster rig from drilling for new oil in the middle of a climate emergency," she said.
"OMV's oil rig is almost 50 nautical miles off the Taranaki Coast. Its remote location means it's nearly impossible for ordinary New Zealanders to take peaceful action to confront it directly.
"We've brought the resistance here to disrupt its chain of support. We won't let this rig carry out its climate-destroying activities quietly, out of sight and mind."
She said representatives from other environmental groups such as Extinction Rebellion, Oil Free Otago and 350 Aotearoa are also involved.
OMV said the blockade was a dangerous action that put people at risk, and protestors were trespassing on a ship that was operating legally.
The company said it hoped it would be able to resolve the situation harmoniously.