Police and anti-vaccine protesters clashed on the grounds of New Zealand's parliament Thursday, with more than 120 arrested after demonstrators who camped outside the legislature for three days were ordered to move on.

Activists chanted the Maori haka and yelled "hold the line", as they scuffled with a phalanx of officers moving to clear a makeshift settlement on the lawns of parliament.

Officers used pepper spray on a number of protesters who dragged two of their colleagues into the crowd, but only minor injuries were reported.

Police moved in early Thursday after taking a hands-off approach to the first two days of protests, warning the crowd to leave or face arrest.

They were punched and kicked amid cries of "this is not democracy", "shame on you" and "drop the mandate".

The protest began Tuesday as a copycat of a "Freedom Convoy" action by Canadian truckers, with hundreds of semi-trailers and campervans jamming streets in central Wellington.

Many of the vehicles left after 24 hours but a hard core of several hundred activists remained, vowing to stay "as long as it takes".

Wellington City Council, which also took a low-key approach in the protest's early stages, said its parking officers had started issuing tickets to convoy vehicles blocking city streets.

Deputy Prime Minister Grant Robertson said patience had worn thin among Wellington residents at the disruption, urging police to act.

"Roads are blocked in the city, businesses have had to shut, people felt threatened and intimidated by some of the protesters," he told Radio New Zealand prior to the police operation.

Police 'disappointed'

Wellington police commander Superintendent Corrie Parnell said more than 150 extra officers were brought in from outside the capital to clear the protest.

"It is disappointing that despite the grounds being officially closed to the public earlier today, a number of protesters are refusing repeated requests to leave the precinct," he said.

In a rare move, authorities closed the parliamentary precinct to the public to prevent reinforcements joining the protest.  

The police edged forward across the parliament grounds but pulled back behind barricades late in the afternoon as demonstrators cheered and claimed victory.

Parnell said it could take days to disperse the crowd, accusing some activists of using children as human shields to frustrate police.

"This was never going to be a short task," he told reporters when the tactics were questioned.

One woman, who refused to give her name, accused police of provoking the crowd.

"This has been a peaceful protest, what they've done is a disgrace," she said.

"I never thought I'd see this in New Zealand."

But locals in the capital have complained about being abused for wearing masks and several businesses near parliament have closed after staff were harassed for enforcing vaccine mandates.

New Zealand requires mandatory COVID vaccinations for people working in sectors such as health, law enforcement, education and defence, with those who refuse the jab facing the sack.

Proof of vaccination must also be shown to enter restaurants, sports events and religious services.

The "Freedom Convoy" of truckers in Canada has gridlocked the capital Ottawa since late last month, prompting city authorities to declare a state of emergency.