Arriving in Amsterdam enamoured by the chocolate-box scenery and picturesque fields of tulips is one thing, but the canal-laced city has a decidedly seedier underbelly to which a quarter of the city's tourists are drawn.

The notorious drug and sex industry attracts a large percentage of the 4 million annual visitors to its bikini-clad bosom. And the "coffee shops", not to be confused with cafés, are an integral part of that itinerary. Indeed, many people are less loved-up by the Delft pottery and flower bulbs and more interested in lounging about with a joint - an attraction that is set to go up in smoke if conservative council members have their way.

The Amsterdam coffee shop, as I discovered on a night out, sells no regular chocolate brownies, and coffee is not a prerequisite on the menu. When I stepped through the doors of the Bulldog, one of Amsterdam's most famous licensed coffee shops, I could smell the sticky, sweet smoke. Patrons, unperturbed by social bias, huddled in their padded booths with reefers gently pressed between their lips. The yellowing walls are covered with old black-and-white photos of drugs being manufactured as well as photographic evidence of some of the celebrity clientele, including David Bowie, Mariah Carey, Snoop Doggy Dog, Sean Penn, and Mötley Crüe's Tommy Lee to name a few.

My curious friends went anxiously to the bar, where a balding middle-aged man took a knowing look and tapped a dimly lit menu fixed to the counter. It was a concise list of the assortment of hashish or dagga on offer, with names like Nirvana Special, Silver Haze, White Widow, and Super Skunk. Prices vary from à3 to more than à50 (R31-R520) but not a single alcoholic drink is in sight. Noticing the blank gazes he recommended a "mild joint" for à3.50 and handed him one, neatly rolled and packed in a plastic blister pack.

The room was claustrophobic with the heady smoke of cigarettes laced with hashish and dagga. We stumbled back onto the street in search of a drink, which happened to be in the bar right next door.

We were certainly not the first but could be some of the last curious tourists to step through the door of one of the 200-odd establishments where foreigners flock to spend their hard-earned euros and pounds at the altar of Mary-Jane. But the shops, which have bobbed and weaved prosecution in a legal grey area for decades, are running out of time to take advantage of the tolerant laws where possession of a small quantity of drugs is considered a misdemeanour rather than a criminal offence.

Under the Dutch Tolerance Policy, that provides the legislation under which the Dutch coffee shops can operate, the shops can sell a maximum of five grams per person of hashish or dagga a day. And it is illegal for them to sell alcohol or to produce their own supplies.

But it gets worse for foreign "stoners"; if new laws proposed in May this year by far-right political leaders are passed, only Dutch citizens will able to enter the cannabis-selling premises and they will be required to sign up for a one-year membership. Each shop will only be allowed 1 500 members.

The government plans to roll out the policy in the southern provinces of Limburg, Noord Brabant and Zeeland by the end of the year and the rest of the country in 2012.

Critics argue the move could negatively affect tourism. Even the capital's town council, backed by the tourist board and local campaigners, is opposing the new measures and the Dutch press recently reported that Mayor Eberhard van der Laan warned that the ban could fuel illegal drug sales and illegal sales of harder drugs.

Nevertheless the red-light district is still far from losing its reputation as a place where you can buy almost anything to satisfy the desires of the flesh. With conservatives set on regulating the sex-industry too, even prostitutes now pay taxes and are subject to regular health checks.

For the purposes of research I tried to persuade my husband to ask a leggy blonde for the price of a happy ending. He declined, fearing "that would be opening the negotiation". But my sources tell me à75 will probably get you laid - though you may have to queue up behind the hordes of sweaty, British bachelor parties that have dressed the groom-to-be in fluffy animal suits.

The whole scene, though eye opening and intriguingly risque, is ultimately somewhat sad. Each Barbie lookalike jiggles and wiggles her wares under a red fluorescent light that transforms the tiny display windows into virtual pink Barbie boxes. There are shops selling all kinds of adult toys and gadgets too, if you dare open that Pandora's box.

But if an awkward giggle is all you are after, you can still put a shiny à2 coin into a slot at a peep show window and watch a couple numbly having sex. Alternatively, you could simply inhale deeply from the sidewalk as you walk past the remaining coffee shops - while you still can.