The Greens have proposed full legalisation of cannabis – including for recreational use – with a new government agency to act as the single wholesaler of plain-packaged cannabis.

People would also be allowed to grow up to six marijuana plants at home for their personal use under the new policy, which was announced by Richard Di Natale on Monday.

The policy is the first time a party with significant federal representation has backed full legalisation, providing a point of difference with the Coalition and Labor, which both support a scheme initiated in 2016 to legalise cannabis for medicinal use only.

Under the plan cannabis would be taxed and regulated in much the same way as alcohol and tobacco. It would be sold to adults by licensed shops and attract GST as well as federal excise tax.

In a statement, Di Natale characterised the policy as a harm minimisation approach that treats “drug use as a health issue, not a criminal issue” and a rational response to the “failed” policy of prohibition.

The Greens’ policy notes that 35% of Australians have used cannabis, according to Australian Institute of Health and Welfare statistics, and there were 79,643 cannabis related arrests in 2015–16, up 6% from 2014-15.

Prolonged use of cannabis can cause dependence, depression and psychological effects, especially if a person has a predisposition to schizophrenia.

But according to the AIHW the impact of cannabis on Australians is dwarfed by the effects of alcohol and tobacco.

A study released in March found that tobacco accounted for 9% of Australia’s combined fatal and non-fatal disease burden and alcohol 4.6%. Illicit drugs were responsible for 2.3% of the disease burden, of which cannabis accounted for only 7%.

Di Natale, a former doctor, said he had “seen that the ‘tough on drugs’ approach causes enormous harm”.

“It drives people away from getting help when they need it and exposes them to a dangerous black market,” he said. “Our plan to create a legal market for cannabis production and sale will reduce the risks, bust the business model of criminal dealers and syndicates and protect young people from unfair criminal prosecutions.”

The president of the Australian Drug Law Reform Foundation, Alex Wodak, welcomed the announcement.

“Banning cannabis hasn’t reduced its use or availability yet it has distracted police from following up more serious crimes, harmed a lot of young people and helped make some criminals rich,” Wodak said.

“Regulating cannabis will give government more control and increase government revenue, which can be used to fund drug prevention and treatment.”

Cannabis is legal in Spain, Uruguay and nine states in the United States, including California. Canada has committed to legalisation this year.

An Essential survey conducted in September 2016 found that 47% of respondents were in favour of decriminalising cannabis, compared with 39% who opposed it and 13% who said they did not know. Support runs as high as 55% when people are asked if cannabis should be taxed and regulated like alcohol or tobacco.

In January the health minister, Greg Hunt, announced a plan for a home-grown industry of cannabis products for export but at that time only 350 patients in Australia had accessed local products.

Labor has accused the government of not doing enough to grant access to medicinal cannabis, particularly for blocking imports of cannabis products.

After the health ministers’ meeting on Friday, Hunt announced that all states and territories had now agreed to a NSW and commonwealth joint trial to provide faster access to medicinal cannabis.

“So there will be a one-stop shop for accessing medicinal cannabis,” he said.

Hunt said after a medical professional prescribes cannabis, a patient should get access within 48 hours and in many cases 24 hours.