The Dutch government on Friday announced it would ban coffee shops from selling "strong" cannabis whose active chemical ingredient, tetrahydrocannabinol (THC), is higher than 15 percent.

"After an amendment in the law, coffee shops will only be able to offer cannabis with a THC content lower than 15 percent," Dutch Vice Premier and Economic Affairs Minister Maxime Verhaging said at a press conference.

"We see cannabis with a THC content above 15 percent as a hard drug, which poses an unacceptable risk" to health, the minister added in The Hague, at the end of the weekly cabinet meeting.

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 percent of cannabis sold in coffee shops in the Netherlands last year had a THC concentration above 15 percent, according to the Trimbos Institute, with an average concentration of around 16.5 percent.

The ban should take effect around March-April next year, the time when the amendment was expected to be passed, justice ministry spokesman Martin Bruinsma told AFP.

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.

Though technically illegal, the Netherlands decriminalised the possession of less than five grammes (0.18 ounce) of cannabis in 1976 under a so-called "tolerance" policy.

Its 670 coffee shops are currently permitted to stock no more than 500 grammes (a little over one pound) of the soft drug at any given time.

Explore further Claims linking health problems and the strength of cannabis may be exaggerated

(c) 2011 AFP