Police are interviewing a former Mt Eden Prison officer following raids on Head Hunters properties today.
The raids led to the arrest of 10 people, including three Mt Eden inmates.
Seven people will appear in court this afternoon charged on counts relating to drugs, weapons and money laundering.
The current inmates will appear in court at a later date.
Detective Inspector Bruce Good said this morning's searches incorporated an investigation into the alleged supply of contraband, such as tobacco and cellphones, to Head Hunter affiliates and other prisoners at Mt Eden Prison. The prison is run by the under-fire private company Serco.
He said as well as the 10 people arrested, police were speaking with two men and one woman in relation to tobacco and cell phones getting into the prison. One of those people was a former Mt Eden prison officer, while the other two were private individuals.
The officer had stopped working at the prison only a few weeks ago when his contract was terminated, independently of the police investigation.
Corrections Minister Sam Lotu-Iiga said the arrests of the three inmates would be included in a review of private prison company Serco's operations at the remand facility.
The Department of Corrections has taken over the Auckland prison's management while a string of allegations of violence and illegal activity are investigated.
"The review needs to take these arrests into account and look into ... what the facts [are] of what's going on in Mt Eden prison," Mr Lotu-Iiga said.
Police launched the raids on the gang's properties across the upper North Island at 6am today.
Nearly 180 officers were involved and properties across Auckland were targeted. Searches were also carried out in Huntly, Ruakaka and Tauranga.
The nine men and one woman arrested face charges including manufacture and supply of methamphetamine, possession of firearms and money laundering.
Police were also speaking with a number of people in Waikato, Waitemata, Bay of Plenty and Northland areas.
At least 16 cars, including a 1958 Ford Fairlane and a 1964 Ford Thunderbird, were seized under the Proceeds of Crime Act. Police were planning to seize assets thought to be worth an estimated $4 million, including bank accounts and property.
Warrants at West Auckland, Tauranga and Huntly were focused on suspected fraudulent car and motorbike licenses issued by three testing companies certified by the New Zealand Transport Agency, Mr Good said.
All up, 34 properties were searched and a few ounces of methamphetamine were found, a number of cars seized and a small amount of cash recovered.
Mr Good said the aim of the operation was to focus on those making drugs, rather than end-users.
"I am concerned about the level of manufacture and distribution of drugs throughout New Zealand up and down the country.
"Where there's crime there's firearms and where there's drugs and firearms and the manufacture of methamphetamine, there's assets, and that's our focus today."
Armed police were this morning at the gang's well-known Marua Road building in Ellerslie, called the Fight Club.
Radio New Zealand reporter Gill Bonnett was at the scene and said three armed police could be seen outside the Fight Club. About a dozen people wearing hoodies were also outside.
Police said the Armed Offenders Squad had been deployed "at several locations" as a precaution.
Detectives from the Organised Financial Crime Agency (OFCANZ) were leading today's operation, assisted by officers from Auckland City, Waitemata, Counties Manukau, Bay of Plenty, Northland and Waikato police districts.
Police said the raids were a phase of Operation Sylvester, an investigation, which had been running for some time, into alleged large-scale production and supply of methamphetamine.
Police Minister Michael Woodhouse said today's actions were part of a strategy to disrupt gangs.
"They are a scourge, all gangs that act outside the law and believe they can do so with impunity need to know the police and the government are going to take this very very seriously."