UPDATE: New Zealand Police have arrested the senior leaders and the majority of patched members and associates of the Bay of Plenty chapter of the Mongols motorcycle gang.

More than 110 police staff, including from the National Organised Crime Group, executed search warrants at 10 properties across the Bay of Plenty region today.

These warrants are part of the final phase of an investigation dubbed Operation Silk.

The 10 people arrested today face a total of 228 charges including: participating in an organised crime group, money laundering, conspiracy to deal methamphetamine, supplying methamphetamine, supplying cocaine, unlawful possession of firearms, and unlawful possession of explosives.

Eight firearms have been located this morning, including two AK47s and two MSSAs (military-style semi-automatic).

This brings the total number of firearms seized off the Mongols over the last four months to 28, and includes AR15s.

Nineteen vehicles were seized today – five motorcycles, one light truck, one heavy truck, seven cars, four utes, and a quad bike.

Other items seized include six Molotov cocktails, ammunition, and various amounts of cannabis, methamphetamine, and cash.

The molotov cocktails seized this morning.

Operation Silk has involved staff from Asset Recovery Units, Bay of Plenty CIB, the Armed Offenders Squad, Police and Corrections dogs, and other specialised search staff.

National Organised Crime Group's Detective Superintendent Greg Williams says the Mongols are a well-established criminal group who are known for drug trafficking, firearms and violent offences.

'The majority of this Bay of Plenty gang were deported from Australia and were from one of the Banditos chapters in Brisbane. This operation sends a clear message that the behaviour of these gangs will not be tolerated in New Zealand,” he says.

'During the course of this lengthy investigation, NOCG has been able to support a Bay of Plenty response to combat and prevent violent incidents stemming from this organised crime group, which have been well documented through the media.

Police seized a number of items during the raids, including vehicles.

'These have been as recent as 12 June and again on 15 June, where senior members are now before the court on serious charges, and a number of firearms and explosive devices have been seized. This proactive action was taken to prevent an attack on a rival gang.”

'What this investigation will allege is that this organised crime group was involved in the sale and supply of methamphetamine and cocaine on a commercial level into the Bay of Plenty as well as across the North Island, causing significant harm to our communities.”

'The ongoing violence between this organised crime group and other local gangs is simply about controlling a share of this drug market, and all these gangs have made it clear that they are prepared to use violence to protect their share.

"This includes not only arming up, but a very clear propensity to use these firearms and commit other violent acts such as arson, serious assaults, aggravated robberies and serious violence, seriously impacting on the wellbeing of Bay of Plenty communities at large,” Detective Superintendent Williams says.

Firearms were also located during this morning's searches.

In total, there have been six known shooting incidents involving the Mongols and other gangs.

Some charges have been laid in relation to these and enquiries continue which will see further people charged.

Western Bay of Plenty Area Commander Clifford Paxton says the efforts of the staff involved in the operation to keep themselves and the community safe in this evolving environment has been pleasing to see.

'I would like to thank our communities for their support and patience in allowing us to bring this comprehensive and lengthy investigation to fruition," says Clifford.

"Not unreasonably, our communities expect action to be taken to ensure their safety, that of their whanau and wider communities."

Cash hiding in a sock draw.

While Operation Silk took place in the Bay of Plenty, Auckland NOCG also ran Operation Nestegg which focused on Auckland-based Mongols.

In May this year, a number of search warrants were executed in Auckland and Tokoroa that were linked to this investigation. Items seized included five firearms, approximately $400k cash and half a kilogram of methamphetamine.

The combined investigations will have a serious impact on the influence and offending of this gang for some time to come.

Police also continue to ask the public for information on another senior Mongols member Brodie Collins-Haskins of Auckland, who is facing several charges.

Brodie Collins-Haskins is still wanted by police.

For any sightings or information in relation to his whereabouts please contact Police.

EARLIER:

Police have carried out a major bust in the Bay of Plenty targeting the Mongols gang and say it has stopped a significant criminal enterprise.

Detective Superintendent Greg Williams of the National Organised Crime Group is expected to provide more details at a media conference in Auckland this afternoon.

The Mongols gang was also targeted in a crackdown on organised crime last month in which more than 90 people were arrested and nearly 50 firearms seized.

The Comancheros, Mongrel Mob, Black Power, Nomads, Head Hunters, Rebels, King Cobras and Tribesmen gangs were also hit the the crackdown during level 3 and 4 lockdowns. More than 100 searches were carried out.

At the time, Williams said 25kg of methamphetamine, 30kg of cannabis and small amounts of other drugs were seized, as well as more than $1.2 million in cash.

Most of the charges related to the manufacture and supply of methamphetamine, supply of cannabis and MDMA, possession of firearms and ammunition, and breaching court bail.