It is illegal to grow cannabis in the Netherlands -- but police will turn a blind eye if there are less than five plants.

"There is major demand from England, Belgium, Germany, France, the Scandinavian countries and at the moment the Baltic countries," said Max Daniel, the police commissioner in charge of the Dutch agency responsible for cannabis-related crime.

Investigations by the Dutch police suggest that around 500 tonnes of cannabis were exported from the Netherlands each year.

"We know that at least 80 percent of production is for export," said Sergeant Daniel.

"In the Netherlands there are 400,000 users of the drug and of hashish."

"If it was only them, the problem would be entirely manageable."

Daniel pointed out that cannabis was no longer a cottage industry -- it has become a growth area for organised crime.

The Dutch government recently set up a task force involving the police, justice ministry officials, energy companies and housing corporations to look at organised crime's role in cannabis cultivation.

Police sources claim that banks are lending to growers, and laboratories tied to universities are working on increasing production.

"We still have the image of the small producer who grows a few plants in his attic to pay for his holidays in Benidorm," he said.

"[But] hemp has a role in almost every major murder, guns and drugs case."