Since 2006, almost £40million worth of the drug has been seized in Scotland, with 302 people arrested. But the Scottish Crime and Drug Enforcement Agency boss Gordon Meldrum insists they still face a fight to stop organised crime gangs turning Scotland into a major international cannabis supplier.

He said: “The sheer number of these seizures would give you an idea it’s not for the Scottish market. It’s the first time Scotland has been turned into a drug producing country and it’s a problem that’s developed in the past five years.

“It’s a significant issue for us to deal with. Cannabis factories are right across Scotland. “Our experience is it tends to be Chinese organised crime groups who run the show and Vietnamese who do the gardening.

“The sizes of operation can differ vastly, from a room in a house to large industrial units.” Officers have already raided 18 cannabis factories in Scotland since the start of this year.

Gangs of crooks rent large houses and spend around £300,000 transforming them into dope farms with special heating and lighting. The Scottish Intelligence Co-ordination Unit has also joined the crackdown on them.

And the Livingston-based investigators will also probe Asian hoods’ links to counterfeiting crimes and prostitution. Meldrum revealed they are also working with DIY stores and power firms to alert them to suspect purchases and high energy bills. He added: “The top 20 most harmful groups in Scotland are now under active investigation. Yesterday we were getting the footsoldiers of organised crime. Now we are after the top men.”

Justice Secretary Kenny Mac- Askill revealed he is set to launch a new campaign against cannabis growers in the autumn. He said: “These crime groups make good people’s lives a misery.”