Environment Minister Nick Smith has laid a complaint with police alleging protesters rubbed rat poison over his face and clothes at the Nelson market.
The Nelson MP has welcomed a drop of poison bait at the Brook Waimarama Sanctuary near Nelson yesterday.
It's been dropped to kill predators and protect native birdlife but there is local opposition to it and three people were arrested there yesterday.
Dr Smith says a couple attacked him at the Nelson market today.
They left once police were called but continued with threats to poison his family.
Dr Smith says the situation became quite frightening when it escalated from verbal abuse to physical shoving.