New Zealanders and Australians are the biggest users of cannabis in the world.

A United Nations report on drug use said cannabis is the most widely used illicit drug.

It is estimated that between 9 percent and 14 percent of the population in New Zealand and Australia use cannabis.

The UN figures group the two countries together under Oceania.

The estimated annual use worldwide of cannabis is between about 3 percent and 5 percent.

The United Nations office on drugs and crime said in 2012, up to about 227 million people worldwide used cannabis, however it said the global use of the drug seems to be decreasing.

In the same year, about 140,000 cannabis plants were eradicated in this country, 119,000 from outside plots, and 21,000 indoors.

Drug Foundation executive director Ross Bell said he was not surprised the use of cannabis by New Zealanders and Australians was the highest anywhere in the world, and that research showed half the adult population here had tried the drug.

The foundation believed if the figures were broken down between New Zealand and Australia, this country would be higher.

Cannabis use was higher here because Australia's approach was more about education over the harm it caused, rather than New Zealand's reliance on policing it and hoping it would go away, Mr Bell said.

The drug was harmful but addressing drug dependency using the justice system did not work, he said.

There were a number of reasons cannabis use was high here, including good growing conditions.

"New Zealand, when it comes to availability of cannabis, it's a drug that we can make in our own back yard, combined with the fact that it's harder to get our hands on other drugs because of our distance and our remoteness, and so we turn to the drug that we're able to grow ... which is cannabis."