Seven people have been arrested for smuggling more than 100kg of methamphetamine inside the bases of outdoor umbrella stands.

Photo: Supplied / NZ Police

Police said Customs intelligence staff flagged a sea freight consignment from China that had been declared as 'outdoor leisure products', including swings, slides, a furniture set, and garden lights.

"Extensive examination" revealed that methamphetamine had been mixed with gypsum hidden in 16 concrete outdoor umbrella stands.

Customs said the meth had a street value of up to $120 million.

Six men and one woman - all foreign nationals - face charges for the importation and possession for supply of a Class A controlled drug, police said.

Customs investigations manager Bruce Berry said "good investigative tradecraft" had uncovered the novel method of drug-smuggling.

"This type of concealment is difficult to detect," he said.

"Transnational criminal syndicates are finding more sophisticated ways to operate and disguise drugs, but Customs and ... police are alert to this, continually developing new techniques and technologies to target and stop them."

Detective Superintendent Greg Williams said police and customs officers monitored the movements of the container, "patiently [watching] the activity around the consignment until they had sufficient evidence to swoop on the targets".

The shipment was linked to a company police believe was set up solely to smuggle drugs, police said.

Several search warrants were carried out in Auckland last week, with further evidence seized.