THE HAGUE (AFP) - Some 17 million visitors flock to Amsterdam every year, but the tide of tourists is now threatening to swamp the historic city famous the world over for its picturesque canals.

Many residents and politicians have decided enough is enough, and are seeking creative ways to control the deluge. With the number of visitors set to reach 30 million by 2030, it's a flood that threatens to overwhelm the Dutch city known as the Venice of the North.

"It's Tuesday and it's raining. There shouldn't be so many people here," sighed Matheus Risso, a 25-year-old Brazilian, sheltering under the arches of the world-famous Rijksmuseum.

But he already had a plan-B up his sleeve, to visit one of the more unusual attractions such as the Sex Museum or the Torture Museum. They are among the lesser known places which city authorities hope could help absorb the overflow from the millions drawn by the red light district or the 'coffee shops' where smoking marijuana is legal.

Today, Amsterdam, which grew from a small fishing village into a major trading hub in the 16th and 17th centuries, has become a victim of its own success. Every year the flow of sightseers flocking to the city of 165 canals grows by some five percent as the result of an impressive marketing campaign.

It has invested almost 12 billion euros (S$18.5 billion) in improving its cultural offerings - from a renovation of the Rijksmuseum home to Rembrandt's haunting painting The Night Watch - to the new water-front Eye film museum, or the secret Catholic church built in a private canal house in 1663 and now opened to the public as the Museum Of Our Lord in the Attic.

"Of course, people want to come and have a look," said Machteld Ligtvoet, spokeswoman for the city's marketing team.

But the result has spawned eye-poppingly long queues outside the biggest attractions with visitors to some places such as the Anne Frank House facing a grim wait of several hours.

For the city's 830,000 permanent residents, the tourist numbers threaten to become a major annoyance.

So much so that Amsterdam officials recently decided to "make some savings" in its marketing budget, according to the city's Socialist Party leader Daniel Peters.

Mayor Eberhard van der Laan has appealed directly to visitors to seek accommodation in other often overlooked cities such as Rotterdam, The Hague and Utrecht, which have regular and good train links with Amsterdam.

"That could save us," he told the Het Parool daily.

He has also put in place tougher conditions for the 170 annual festivals which attract more than 2,000 participants, such as limiting how many can be held in each park every year.

Visitors spend about 10 billion euros a year in the country and the tourist industry supports over 100,000 jobs in Amsterdam.

But there are concerns that what is now an irritation could fester into a more permanent anger among locals fed-up with litter-strewn streets and clogged roads.

"We have to ensure that we don't exceed the levels of visitors that we've reached and seize the problem by its horns," said Marjolein Moorman, leader of the city's opposition labour PvDA party.

"Amsterdam has an historic city-centre, therefore its streets are small and narrow. If tour buses, beer bikes, and bicycle taxis are all trying to get through, the streets are too small. That can cause people to lose their tempers," she added.

Among her creative solutions would be to bar large tour buses from the centre; track more closely private apartments let to vacationers via such sites as Airbnb, cutting the number of days they can be sub-let a year to 30 from 60, and cut museum queues.

Some attractions are already trying to promote more online ticket sales, giving visitors a timed window for entry. The city is also trying to attract more people outside of the summer season, with such things as the Christmas winter light show along the canals.

But with Amsterdam in easy reach of many European countries and served by many budget airlines, such measures will not be enough to bring total relief, Moorman said.

Hence the suggestion to travel outside the city to less well-known spots such as the UNESCO world heritage site of the fortress stretch resplendent with medieval castles, or the beaches at Zandvoort, the windmills at Zaanse Schans, and beautiful tulip fields at Keukenhof.

"Yes, of course, you can have a look at the canals, but also have a look at other neighbourhoods to the north or the south or upcoming east for example," said Ligtvoet.