Police today executed three further search warrants in Waikato and Bay of Plenty, with a total of 18 search warrants conducted yesterday and today.
As a result of the operation a total of 17 people, ranging in age from 19 to 66, are facing 263 charges.
Police today located three loaded AK47 and two MSSA (military-style semi-automatic) firearms, bringing the total number of firearms seized over the two days to 13.
Superintendant Greg Williams of the national organised crime group said in a statement that police can now confirm that one of the firearms seized yesterday was a MP38 submachine gun.
Williams yesterday said that most of those arrested had been deported from Australia and were from one of the Bandidos chapters in Brisbane.
Since January, there have been six shootings in the Bay of Plenty involving the Mongols and rival gangs.
The Mongols have also been linked to arsons, aggravated robberies, serious assaults and other violent attacks.
The three people arrested today will face charges including participating in an organised crime group, unlawful possession of firearms and conspiracy to deal methamphetamine.
They will appear in the Tauranga District Court today.
Police expect there will be further arrests in relation to the operation, Superintendant Williams said.
Police are still seeking any information on the whereabouts of senior Mongols member Brodie Collins-Haskin of Auckland, who is facing several charges.