Updated 1.43AM: A spirited crowd of about 100 people has turned out to a protest at Auckland's Mount Eden Prison.

They're demonstrating against the privatisation of New Zealand jailsfollowing recent scandals which have beset Mt Eden and its operator, Serco.

Labour MP Kelvin Davis is among those who are addressing the crowd.

"The ideal scenario is for Serco to get booted out of New Zealand," he said. 

"They should never be allowed to come anywhere near prisons. They're cutting corners, they're allowing people to be violated, broken, [and] battered."

"The government needs to step up here, they haven't given them a written warning as far as I'm aware."

Organiser John Palethorpe is from the UK, where he says Serco has also had many failings.

"Given what's happened at Mt Eden in the last few weeks, I thought, time to do something."

Palethorpe said prisons should not be for profit, and the only dividend should a be a social one where prisoners leave prison less brutalised than when they went in, ready to contribute to society.

"New Zealanders are right to ask why their taxpayer money is being used to fund a foreign company's profit margin - and the public service they are supposed to be providing, isn't being provided properly."

Corrections has taken over the running of Mt Eden Prison while a review is carried out into Serco's management. It's already facing penalties of at least $500,000, but the Government says it could lose its contract altogether if it's not living up to the agreed conditions.

Among the incidents which have arisen are violence, contraband, and the use of cannabis and alcohol behind bars.

This week three Mt Eden inmates were arrested for allegedly helping to run a methamphetamine ring, while a former guard is also being investigated.

The Public Service Association, which represents 3,000 Corrections staff and 100 more at Serco’s two private prisons, said the Government should commit to no more "prison experiments".

"As a nation we can’t continue to allow private companies to come in and profit from people’s misery," says its National secretary Erin Polaczuk.