Two protesters have been arrested following a confrontation with police north of Auckland's Harbour Bridge on Saturday.
A large group of anti-1080 protesters were partaking in a hikoi to Parliament when they were met with an "enormous police presence", according to lawyer Sue Grey who was among those protesting.
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Ms Grey estimated there were between 40 and 50 police officers blocking the road from Onepoto Domain as the group were preparing to cross the Harbour Bridge.
"The whole thing just turned ugly in moments from the police conduct," she said. "It was just unbelievable; it was like walking into a nightmare. They were extremely firm and in some cases physically assaulting people. It was a very frightening scene that I've never come across before."
Police Inspector Alisse Robertson said a 52-year-old man had been arrested for assaulting police and obstruction, while a 47-year-old woman had been arrested for obstruction.
Insp Robertson said this followed the group being warned not to attempt to walk across the bridge.
"The group has chosen to ignore this advice, and despite numerous attempts by police staff to look at alternative options, they have refused to negotiate."
Ms Grey claimed the protesters were planning to use buses and cars to travel across the bridge and police "completely misread the situation".
But Insp Robertson said it wasn't until the last moment, when the two people had already been arrested, that the protesters got onto a bus.
Ms Grey claimed that while attempting to provide legal assistance to those arrested she was assaulted by two different policemen.
"A lot of people [were] absolutely shocked. They've never been involved in any scenes like that in New Zealand before."
In a Facebook Live video, police were seen blocking the road leading from the domain, which is a couple of blocks from an entrance to the motorway.
Protesters were heard screaming "no more poison", while police responded, saying, "We are here for your safety."
The video showed several scuffles between police and some protesters.
Ms Grey said she hoped the protest would spark a conversation in the public about 1080 poison and what she said was a lack of public forum provided so far.
"New Zealand's being poisoned and our water supplies are being intentionally poisoned by the New Zealand Government... The Government don't seem to think it's an issue at all."