The UK should have a legal, digital-only cannabis market in the UK, according to a new report.

The regulated market would limit access to anyone younger than 21, with checks similar to buying alcohol online.

The report, from pro-drug legalisation think tank Volte Face, argues that a controlled market would offer safer products and offer the ability for revenues to be taxed - potentially raising around £800m for the exchequer.

"We believe that Britain's multibillion-pound cannabis market should be developed and operated exclusively online by a private sector that is stringently controlled and regulated by democratically elected governments," the report, called The Green Screen, argues.

But anti-drugs campaigners have called the suggestion an "opportunity for national disaster" and "absolutely the most irresponsible thing to do".

Around 2.1 million people use cannabis every year, according to government figures, despite it being illegal.

Mike Power, the author of The Green Screen report, told Sky News: "The current situation, any young person with five or ten pounds can come to Camden and buy a bag of cannabis.

"They can't go to a supermarket and buy alcohol without having their identity checked and verified."

"We would argue that a digital model would enable that to be the case. So that every purchase would have to have age and ID verified before you actually bought it.

"As well as that, it would mean that you could tax every single purchase, and monitor it, and make sure that money was going directly into the taxpayers' pocket."

Power argues that a digital-only market would circumvent objections to cannabis cafés, as in the Netherlands, or the shops that are starting to appear in certain US states - both in terms of attracting young people and concerns over antisocial behaviour they might bring to neighbourhoods.

Other countries, including Portugal and Lisbon, have taken or announced measures towards decriminalising cannabis. Volte Face has advised the Canadian government on methods.

Elizabeth Burton-Phillips, the founder of support charity DrugFAM, told Sky News: "It's not a credible argument".

"My personal story is sadly losing one of my sons at the age of 27 as a result of his addiction to drugs, which began with using cannabis - the gateway drug.

"[For] vulnerable young people - particularly those who are willing to try anything in their teenage years - this is just opening up an opportunity for national disaster.

"It's absolutely the most irresponsible thing to do."

Shaun Attwood, a former drugs dealer and now an author and activist for drugs legalisation, told Sky News that a digital cannabis market would deprive organised criminals of millions of pounds.

"The illegality of drugs creates an inflated black market price.

"I take full responsibility for what happened to me. On 16 May 2002, a swat team smashed my door down. And I ended up in the jail that's got the highest rate of death in America."

"If there had been an online legalised marketplace for drugs, job opportunities for dealers would have ceased to exist. I couldn't have arbitraged that price from Holland over to America because the users would be buying the drug online.

"So I'd have been taken out of the loop completely."