More than $2.4 million in cash, firearms, methamphetamine and cannabis have been seized as part of an investigation into the New Zealand chapter of the Hells Angels Motorcycle Club.

Operation Samson is investigating people and entities connected to the group. Search warrants were executed at residential and commercial addresses across Auckland in the past week, resulting in the seizures.

Detective Inspector Albie Alexander of the police National Organised Crime Group said the investigation continued to shed light on the activities of the trans-national organised crime group, and further arrests and charges were possible.

A 30-year-old patched member of the Hells Angels had been charged with money laundering and had appeared in the Auckland District Court.

Such offending undermined the wellbeing of New Zealand's communities, Alexander said. Police would keep targeting those who accumulated assets and wealth through illegal means.

"In conjunction with Operation Cobalt, we will also continue to target and suppress illegal gang activity in order to enhance the safety of our community and staff – and hold those responsible for this type of offending, to account."

He acknowledged the "outstanding work" of the investigation team, and the help of partner agencies in New Zealand and overseas.

"We are all committed to disrupting and dismantling these illegal trans-national networks operating in New Zealand."