Police have seized firearms and more than 34,000 cannabis plants and 79kg of dried cannabis with a combined street value of around $95 million in a major summer crackdown on drug crime.

The nationally coordinated operation was conducted across several regions of New Zealand as part of a wider cannabis investigation and prevention operation.

National Organised Crime Group Director Detective Superintendent Greg Williams said the eradication operation was just one element of Police's ongoing work to reduce the impact of drugs and organised crime in our communities.

"The aim of the operation was squarely on commercial-scale cannabis growing and the organised crime groups behind them," said Williams.

"This was not about personal cannabis use or low-level offending.

"There were 123 searches executed which resulted in 80 firearms being seized, showing the very concerning link between illicit firearms and drug dealing. This work continues and aligns to Operation Tauwhiro."

A spokesperson said during the operation 81 people were spoken to by police, mostly about cultivation of cannabis, possession for supply of cannabis, and firearms offences, and many warnings were issued for cultivation of small-scale plots.

Two dozen indoor commercial cannabis grows were discovered and dismantled during the operation.

In addition to the cannabis, police said 4kg of amphetamine and 19g of methamphetamine were seized.

"Police will continue to focus on the distributors of more harmful drugs, such as methamphetamine and synthetics. But it is important we continue to put pressure on those who profit from running any commercial illicit drug operations," said Williams.

"The primary focus of this operation was on cannabis eradication of large-scale growing operations from the air, in areas of New Zealand where we know they are likely to be, and at the same time ensuring we are deploying our resources where we can make the biggest impact."

Investigations into those involved the cultivation of the seized cannabis were ongoing, and further arrests were expected in the coming weeks.