Three Tongan men have been found guilty of conspiring to import and sell methamphetamine - despite the stash never existing.



David Charles Mafi, Douglas David Afeaki and Peter Lawrence Tanginoa were found guilty by a jury at the High Court in Auckland today.



The trial before Justice Judith Potter lasted three weeks.



Tanginoa was accused of conspiring to import a class A drug - methamphetamine or P - into New Zealand from associates in Tonga.



Mafi and Afeaki were accused of conspiring to supply P once the drug had landed in the country.



Two other men, Angus Naupoto and William Wolfgram, have also been charged with conspiring to import the drug but were not on trial.



All the men were charged with participating in an organised criminal group.



Importing, manufacturing and possession for supply or dealing P can attract a sentence of life in jail.



At the start of the trial, Crown prosecutor David Johnstone told the court the trial was about "pretend drugs these three men thought were real".



"This is not a thought crime - it went beyond that," Johnstone said.



The court heard Naupoto travelled to Tonga and entered into an agreement with his associates to import 20kg of P.



Tanginoa and his cousin, Wolfgram, enlisted people in New Zealand to invest in the scheme so that the group could import the drugs.



Wolfgram then enlisted Afeaki and Mafi who conspired to distribute the methamphetamine for "commercial gain".



Police started investigating the group in July last year after they had uncovered a deal between three men and a Tongan syndicate to import a stockpile of P into New Zealand.

Tongan police became involved in the investigation and members of the alleged drug syndicate were searched and interviewed.