One of the world's largest cannabis companies is positioning itself for recreational marijuana use to be made legal in Australia, amid fresh political debate about the proposed reform.

Canopy Growth Corporation, a $5.6 billion publicly listed Canadian company, has taken out Australian patents for a range of marijuana products including its global, youth-focused "Tweed — feel free" brand for medicinal and recreational cannabis.

The company has also hired political lobbying and research firm Crosby Textor to help it in discussions with the federal and state governments, following Australia's decision in 2016 to legalise cannabis for medicinal use.

A Four Corners investigation into Australia's booming medical marijuana industry reveals major players are optimistic about the legalisation of recreational cannabis in Australia.

Medicinal cannabis has been legal in Canada since 2001 and recreational marijuana use will be legalised for adults as early as August.

Bruce Linton is the founder of Canopy Growth Corporation, one of Canada's biggest cannabis companies.

His expectations for the Australian market are high.

Bruce Linton founded one of Canada's biggest cannabis companies, Canopy Growth Corporation. ( Four Corners )

Mr Linton said Canopy's view is that once a country allows medicinal cannabis, it is inevitable that legalisation of recreational use will follow.

"Every country that's federally legal, we think someday will start with medical," Mr Linton said.

"And the reason is, it isn't being introduced as a new thing.

"It exists everywhere in a large volume and so we think it's just a natural progression.

"So Australia, Germany, everywhere … it is kind of the mandate.

"Prepare for the future, have things ready."

'Medical cannabis is the Trojan horse'

Ross Smith says the issue of legalising recreational cannabis use has become less taboo. ( Four Corners )

Cannabis industry analyst Matthijs Smith, whose investment bank Canaccord Genuity holds stock in one of Australia's largest medicinal marijuana companies, Cann Group, noted this shift had occurred in some countries.

"It's been interesting that a number of jurisdictions, such as Canada, Uruguay, and states in the US, once they have made cannabis available for medical purposes, and they've seen that that hasn't resulted in a whole deterioration of society, have become a lot more liberal and contemplated or indeed enacted the recreational use," Mr Smith said.

Jacinda Ardern has pledged to hold a referendum on legalisation of recreational cannabis before the 2021 NZ election. ( AAP: Mick Tsikas )

A founder of the Australian cannabis industry, venture capitalist Ross Smith, told Four Corners: "There's no question in my mind that medical cannabis is the Trojan horse for recreational cannabis and I don't believe it's a bad thing."

Recreational use is legal in eight US states and the District of Columbia.

In New Zealand, Prime Minister Jacinda Ardern has pledged to hold a referendum on legalisation of recreational cannabis before the next national election in 2021.

Asked if he had a view about legalising recreational cannabis use, federal Health Minister Greg Hunt told Four Corners: "It's not something that the Commonwealth is proposing, but it is a matter for individual states, under the constitution."

However, last week Mr Hunt denounced a policy to legalise recreational marijuana announced by federal Greens leader Richard Di Natale.

Federal Health Minister Greg Hunt has denounced a Greens policy to legalise recreational marijuana. ( AAP: Daniel Munoz, file photo )

Senator Di Natale has proposed regulating the sale and use of marijuana by adults in Australia, which he said would raise hundreds of millions of tax dollars.

Mr Hunt slammed the policy as "open slather for a highly addictive and dangerous drug".

Last month a parliamentary committee recommended that the Victorian Government establish an advisory council to consider a range of drug policy issues.

It said the council should "investigate international developments in the regulated supply of cannabis for adult use, and advise the Victorian Government on policy outcomes in areas such as prevalence rates, public safety, and reducing the scale and scope of the illicit drug market".

The 2016 National Drug Strategy Household Survey found cannabis was the most commonly used illegal drug, used by 10.4 per cent of people in the previous 12 months.

It found that 35 per cent of Australians support the legalisation of cannabis, up from 26 per cent in 2013.

"Community tolerance has increased for cannabis use, with higher proportions of people supporting legalisation and a lower proportion supporting penalties for sale and supply," the report by the Australian Institute of Health and Welfare said.