Several sika deer have been illegally released into North Taranaki forests and the Department of Conservation says it was part of a protest against 1080.
Lou Sanson, DoC's director-general, slammed the release as "sabotaging community projects that are working towards Predator Free 2050".
"The illegal release is the action of selfish and short-sighted individuals working against the aspirations of many thousands of people in local communities, including Taranaki, to keep our forests intact and return them to their rightful inhabitants," he said.
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Five deer has been tracked down and culled so far. Police are investigating the incident but were unable to confirm to Newshub just how many had been released.
"Police would like to hear from anyone that has seen deer being moved in and around the Taranaki area," a spokesperson said.
The sika deer could spread tuberculosis, threatening nearby farms, Mr Sanson said.
"Valuable resources are now being diverted from important conservation work that would benefit Taranaki."
The 1080 poison is commonly used across New Zealand to kill pests, but protests have been fierce.
As well as the deer-release, DoC said the window of a staff member's car was smashed last week. Ramped-up protests over the past few months have also seen wheel nuts allegedly loosened on staff vehicles, while 1080 pellets were left in a DoC letterbox.
"Lawful protest is fine, but potentially putting people's lives at risk with irrational behaviour has to stop before someone is hurt," Mr Sanson said.
At the time of the previous protests Forest and Bird CEO Kevin Hague said it was out of control.
"Forest and Bird is appalled by the reported behaviour of loosening wheel nuts and that kind of thing that places people's lives at risk. That's just intolerable."
Mr Hague said 1080 isn't his preferred method of pest control but agreed it was effective.
Anyone who has information about the deer release or window breaking is urged to contact the Department of Conservation or the police. Information can also be provided anonymously to Crimestoppers on 0800 555 111.