A handful of the Netherlands’ medium sized cities have come forward to take part in the government’s controversial regulated marijuana experiment but the five biggest cities have all said no, the Volkskrant said on Monday.

Tilburg, Almere, Breda and Nijmegen had signed up for the trials by the June 11 deadline and Groningen is also considering the idea, even though the city’s 12 cannabis cafes are opposed, the paper said.

The experiment with regulated growing is supposed to remove the gray area between the sale of marijuana in council-licenced coffee shops and the illegal cultivation and supply.

However, there are so many problems with the proposals that the big cities, where most of the coffee shops are located, see no point in taking part.

One issue is with the four year trial period, which will not be extended, even if the experiment is successful. This means that coffee shop owners will be forced back into the illegal circuit after four years of selling ‘legal’ marijuana.

Another objection is the requirement that all coffee shops within a council area take part in the scheme. In Amsterdam, with 175 coffee shops, this would be impossible to control, mayor Femke Halsema said.

In addition, the coffee shops would not be allowed to sell any ‘foreign’ hashish, which currently accounts for up to 25% of sales. This would drive users into the illegal circuit, experts say.

The conditions for the experiment still have to be approved in the lower house of parliament.