NZ First leader Winston Peters tours Parliament protest camp as police prepare for another showdown in central Wellington

There was chaos on the streets of Wellington early on Tuesday morning as police with riot shields attempted to shrink the perimeter of the anti-mandate protest. 

People screamed as a white car sped towards a line of officers, braking just in time. Police tried to smash windows as they pulled the driver from the car and took him away. 

Three people were arrested and three officers were taken to hospital after being sprayed with an unknown substance. 

And on the occupation's most violent day, an old political figure returned to Parliament to embrace the demonstrators. 

It was the rudest awakening on the streets of Wellington. Another early morning advance on the battle line - protesters versus police - this time with complete riot shields. 

It was complete carnage. A car was driven into the backs of police officers as they held a line. The driver was ripped from the car and arrested. 

"What we saw this morning was concerning and disgraceful, we've dealt with that individual appropriately," said Assistant Police Commissioner Richard Chambers. 

Prime Minister Jacinda Ardern condemned the actions of the protesters.

"It's disgraceful. The police are there doing their job to keep Wellingtonians safe," she said in Auckland. "To have them met with such acts of violence is just totally wrong."

Police faced unmitigated mayhem. The riot gear was necessary. 

"We had information to say more human waste was going to be thrown at the police officers," Chambers said. 

This time it wasn't faeces. Three officers were injured as protesters sprayed an unknown stinging substance in their eyes. 

"I did contact the commissioner because I was concerned for his staff's safety and from what I was seeing reported," Ardern said. 

Police were not the only ones injured in the altercations. A man could be seen with his face bloodied and bruised. 

It was all part of a mission to shrink the size of the occupation. 

The operation saw police move concrete barriers 50 metres on Hill St, 50 metres on Aitken St and take 100 metres of Molesworth St back from the occupiers. 

When asked why the police didn't do it weeks ago, Chambers told Newshub: "I think the last two days have demonstrated that police are making good progress."

While the protest is shrinking, tensions are rising. As police and protesters took a break from their beef during the day, tonight the cops are suited up and ready for another riot - this time many wearing protective goggles.

They have been forming a battle line, taking back more of the streets. A day that began with violence ending with a showdown that looks set to stretch into the night. 

On Monday evening when it spilled onto the streets, one man let off fireworks, another throwing bottles at the cops. 

Some of the protesters believe the troublemakers are either government or police plants. 

Asked if there was any evidence, Chambers said: "Ah, no."

There are also suspicions other actors are infiltrating the protest to make them look bad. 

"That is unacceptable behaviour. But is it part of what is a legitimate protest or is it people purposefully coming in to overthrow it? I don't know," said former New Conservative leader Leighton Baker who is involved at the protest.

The camp on Tuesday was infiltrated by former Deputy Prime Minister Winston Peters, who did a walkabout around the camp. 

The NZ First leader was flanked by the head of the Sensible Sentencing Trust - former NZ First MP Darroch Ball - mixing mask-free in the illegal occupation. 

Peters refused to talk to Newshub. 

"I'm not being interviewed by you, so go away," he said into the camera. 

His posse wouldn't allow it, manhandling when attempts were made. 

The Prime Minister scolded politicians for opportunistically trying to capitalise on discontent. 

"What's happening in Wellington is wrong and I don't care which political party you're a member of."

But for some - the down and out - it's obviously too hard to resist.