A drug expert says a clever chemist has been at work...disguising methamphetamine as dishwashing liquid.

LISTEN ABOVE: Larry Williams talks to the professor of Toxicology at the University of Canterbury, Ian Shaw, about exactly what T-Boc meth is and how it works.

But the deception wasn't clever enough to prevent four men standing in the dock at Auckland District Court today.

They're charged with importing around 160 litres of a substance known as t-boc, which is a form of meth chemically masked to prevent detection.

Canterbury University's professor Ian Shaw said the drug makers knew what they were doing.

"They've taken meth, and they've added a molecule to it and then exported it with that molecule added to it and then they take the molecule off afterward"

It's believed to be the first time this form of meth has been seized in New Zealand.

 

Detective superintendent Dave Lynch said their investigation relied on international partners, including Chinese Narcotics Control Commission.

"Certainly the assistance from them around the initial intelligence was pivotal in terms of being able to get the result on this particular investigation."

Lynch said the battle against methamphetamine is ongoing.

"We remain committed to do what we can to cut off the supply chain coming into New Zealand."