Campaigners in the Netherlands are urging people to vote for pro-marijuana political parties in September’s parliamentary elections, in an effort to change a law that restricts sales of cannabis to foreigners.

They are hoping to overturn a decision that will mean from January 2013, only Dutch residents with a ‘cannabis card’ will be able to buy the drug – even in Amsterdam.

That law has already gone into effect in Maastricht, which is near the borders with Germany and Belgium and which attracts an estimated 1.4 million “drug tourists” each year mainly from those countries and France.

It effectively transformed local coffee shops into private clubs. Not only can they sell only to Dutch residents, but customers are required to sign up with their cafe of choice.

Each shop is allowed a maximum 2,000 “members” who must be at least 18-years-old.

Although cannabis is technically illegal in The Netherlands, the country decriminalised possession of less than five grammes in 1976 under a so-called tolerance policy, but it can be sold only in the specialised coffee shops.

Left-wing opposition parties — including the current largest Labour Party (PvdA), the Socialist Party (SP) and the Party for Animals (PvdD) have said they were against the current law.

“We will do everything to get the ‘cannabis-card’ law off the table,” Socialist Party MP Harry van Bommel said in a video interview published on the Dutch pro-weed news site www.coffeeshopnieuws.nl. He added: “This law is part of the problem, not part of the solution.”

The PvdA in a statement on their website suggested that coffee shops simply be replaced by “cannabis shops”, with the sale of marijuana legalised but strictly controlled.