Armed police uncovered a large drug lab and a significant amount of methamphetamine when they swooped on a Hamilton property today.

The house in Melville was one of three properties searched during a multi-agency drug bust known as Operation Maxine.

Detective Senior Sergeant Nigel Keall said two men, aged 48 and 51, were arrested at the address.

Police also uncovered a handgun, a large quantity of methamphetamine and a "sophisticated methamphetamine laboratory".

Lab equipment and chemicals were seized, but police said it would still take some days to examine and clear the property.

Police also searched properties in Koromatua and Ngahinapouri.

The operation involved a combined team of police from Waikato, Bay of Plenty, Wellington and Auckland, including armed offenders squad members.

Mr Keall said armed officers were needed because drug dealers had shown a willingness to arm themselves to protect their illegal investments.

"These concerns were justified during our search of the properties with the discovery of a handgun."

The operation also involved police clandestine lab team members from Auckland and Wellington, ESR forensic specialists, firefighters and ambulance staff.

"The use of staff from other districts to support large scale investigations like today's is nothing new and demonstrates the police's willingness to apply a whole of policing approach to organised crime," Mr Keall said.

"When you have an investigation such as today's a variety of investigative options have to be explored to develop a solution that is fit for purpose."

Two men will appear in Hamilton District Court tomorrow charged with unlawful possession of a pistol, manufacturing methamphetamine and possession of equipment with the intent to manufacture methamphetamine.

- APNZ