AUSTRALIANS are world-class dopes, according to research.

And police say Victorians are doing more than their bit to keep the nation up in cannabis smoke.

The study, one of three in a series about addiction to be published in The Lancet today, found more than 200 million people used illicit drugs globally, with those in wealthier countries most likely to abuse illicit substances.

It found Australia and New Zealand were the highest users of cannabis in the world, with up to 15 per cent of 15 to 64-year-olds having used the drug at least once in the past year.

Study co-author Louisa Degenhardt, of the National Drug and Alcohol Research Centre, said the popularity of illicit drugs was linked to cost and supply.

"There's more that we need to understand about that, but we think that, particularly for occasional users, if drug prices go up then their level of use goes down," Prof Degenhardt said.

Victoria Police has seized record amounts of cannabis in recent years, confiscating 9000 plants in a two-day blitz a little over a year ago.

Sen-Sgt Jim Sutherland, who leads the fight on drugs in Victoria's outer eastern suburbs, said police were shutting down cannabis-growing houses at a rate of about one a week.

"Cannabis users are a dime-a-dozen," Sen-Sgt Sutherland said.

"What we're concerned about is high-level cannabis cultivation and trafficking.

"We think there are a lot of crop houses out there and what we do is just the tip of the iceberg."

He said organised criminals could make as much as $4000 a plant and have 50 plants in one house.

"You have a short grow cycle and you can understand there is a lot more money to be made out of cannabis trafficking than out of heroin," he said.

Originally published as Australians are world-class dopes