Greens Leader Richard Di Natale is calling for bipartisan support to overhaul Australia's drug policy so it is in line with Portugal's, where drug use is treated as a health, not criminal, issue.

The Victorian senator is on a self-funded, fact-finding mission, meeting policymakers and program developers in the European country.

Greens Leader Richard Di Natale says Portugal has seen a huge decline in all the things associated with harmful drug use. Credit:Andrew Meares

Since 2001, drug users in Portugal are no longer put through the criminal justice system.

The funds saved from enforcement have been used to increase access to drug treatment and prevention, including rehabilitation services, in the country.