UPDATED 3.56PM: Three inmates from Mt Eden prison have been charged after today's drug raids on Headhunter properties in Auckland.

Alicia Burrow reports police are also speaking to three other people, including a former prison guard.

"The employment of a former guard was terminated a few weeks ago, but we aren't sure who the guard was or why they were terminated."

Detective Inspector Bruce Good says a former guard is being questioned over the alleged supply of contraband such as tobacco and cellphones to prisoners.

Minister Sam Lotu-Iiga doesn't want to comment on the possible involvement of a guard.

"Well I get a heads up of what's going on, and then I allow the police to do their job."

Three inmates and another seven gang members will appear in the Auckland District Court this afternoon.

The arrests are another in a string of troubles for the Serco-run prison, which is facing allegations of a culture of prisoner violence. 

Sam Lotu-Iiga says he's disappointed, but Serco still won't have its contract cut yet.

"It's too early to speculate about what we do in terms of Serco's contract but we've got a review in place. We need to get to the bottom of these facts."

Labour's corrections spokesperson Kelvin Davis believes this should have been the final nail in the coffin for Serco's contract.

"They're not even on a written warning yet so there's still that process to go through and that's what we were calling for last week, for a written warning to happen so the next breach, they're gone."

Almost 180 police officers stormed more than 30 properties across Auckland with search warrants this morning. 

Searches were also underway in Huntly in Waikato, Ruakaka in Northland and Tauranga. Police said the operation was targeting criminal activities of the gang in Auckland as well as parts of the Bay of Plenty, Waikato, and Northland.

Detectives from the police's Organised Financial Crime Agency - which is leading the operation - are being assisted by officers throughout the districts.

The raids bring to a close Operation Sylvester - a police investigation into Head Hunter activities which include alleged large-scale production and supply of methamphetamine.

Detective Inspector Bruce Good said police were also planning to seize assets worth about $4 million, including a large number of high-end cars, machinery, bank accounts and property.

He said the "ripple effect" the criminal offending had on law-abiding New Zealanders could not be underestimated.

"This is not about targeting people solely because they are in a gang.

"It's about their criminal activity which continues to drive crime, that in turn affects all of us throughout New Zealand."

A number of people have been detained by police in the last few hours and were now being interviewed in relation to manufacturing and supplying meth, money laundering, unlawfully possessing firearms and fraud.

Philip King was driving to his furniture restoration business about 6.10am when he saw police cars blocking off Marua Rd and Burke Rd, forcing him to take a back road to work.

"Apart from two police cars -- one's lights flashing and one's lights not -- there wasn't a lot else to see."