Police Commissioner Andrew Coster has said Wednesday's major operation at the Parliament protest was brought on due to "an escalation in concerning behaviour" from those still present in Wellington.
Coster spoke to media on Wednesday after 36 people were arrested, 15 vehicles were towed and three police officers were injured earlier. He said that while de-escalation was the preferred option of those involved that option was no longer available.
"During a period of engagement with the protest leaders, we were able to get in place tactics that de-escalated both the number of vehicles and people at the site," Coster said.
"However, we've reached the stage where protest leaders were either unwilling or unable to effect meaningful change, particularly to the behaviour and the impact of the protest on Wellington."
Part of that change was a growing number of non-peaceful protesters at the site, Coster said.
"We've become concerned that those with good intentions are now outnumbered by those with a willingness to use violence to effect their means," he said.
"We have observed an escalation in concerning behaviour which has ultimately resulted in today's action."
Coster added Wednesday's operation along with previous actions carried out were not about preventing lawful protests but instead keeping people safe.s
"This particular protest though has reached a stage where the harm being done far outweighs any legitimate protest," he said.
"The balance has tipped and it's time to bring this to an end."
Coster said they will continue the operation until all protesters have left, regardless of how long it takes.
"We will continue to arrest and charge people where necessary and will continue seizing vehicles throughout the day.
"When the job is done, then we will be finished."