|"Coffee shops" are a major tourist attraction in Amsterdam [GALLO/GETTY]
The Dutch government has said it will move to classify high-potency cannabis alongside hard drugs such as cocaine and ecstasy, the latest step in the country's ongoing reversal of its famed tolerance policies.
The decision means most of the cannabis now sold in the Netherlands' weed cafes - known euphemistically as "coffee shops'' - would have to be replaced by milder variants.
But sceptics said the move would be difficult to enforce, and that it could simply lead many users to smoke more of the less potent weed.
Possession of cannabis is technically illegal in the Netherlands, but police do not prosecute people for possession of small amounts, and it is sold openly in designated cafes. Growers are routinely prosecuted if caught.
The government said it would ban coffee shops from selling "strong" cannabis whose active chemical
ingredient, tetrahydrocannabinol (THC), is higher than 15 per cent.
"We see cannabis with a THC content above 15 per cent as a hard drug, which poses an unacceptable risk," said Maxime Verhaging, the Dutch Vice Premier and Economic Affairs Minister, at a press conference in The Hague.
The minister said weed containing more than 15 per cent of THC is so much stronger than what was common a generation ago that it should be considered a different drug entirely.
The high potency weed has "played a role in increasing public health damage,'' he added.
The intensity of psychoactive effects of cannabis depends on its THC concentration, said the Trimbos Insitute, which penned a report used by the Dutch government.
About 80 per cent of cannabis sold in coffee shops in the Netherlands last year had a THC concentration above 15 per cent, according to the Trimbos Institute, with an average concentration of around 16.5 per cent.
The Cabinet has not said when it will begin enforcing the rule, but the ban could take effect around March-April next year, the time when the amendment was expected to be passed, justice ministry spokesman Martin Bruinsma told the AFP news agency.
The spokesman said municipalities would be able to order coffee shops selling "strong cannabis" to close its doors, a sanction which could be added on top of any legal procedure.
The Dutch Justice Ministry said on Friday it was up to cafes to regulate their own products and police will seize random samples for testing.
But Gerrit-Jan ten Bloomendal, spokesman for the Platform of Cannabis Businesses in the Netherlands, told the Associated Press implementing the plan would be difficult "if not impossible".
"How are we going to know whether a given batch exceeds 15 per cent THC? For that matter, how would health inspectors know?'' he said. He predicted a black market will develop for highly potent weed.
The ongoing Dutch crackdown on cannabis is part of a decade-long rethink of liberalism in general that has seen a third of the windows in Amsterdam's famed prostitution district shuttered and led the Netherlands to adopt some of the toughest immigration rules in Europe.
The number of licensed cafes has been reduced, and earlier this year the government announced plans to ban tourists from buying weed. That has been resisted by the city of Amsterdam, where the coffee shops are a major tourist draw.