Switzerland's first ever drive-in "sex boxes" were opened in the city of Zurich on Monday in an attempt to force illegal prostitution out of the inner city, combat organized crime and make the sex industry safer for women.

Despite being perceived as a clean and conservative-minded city, Zurich has a burgeoning red light district. The city has struggled to fight gangs, particularly from Eastern Europe who traffic women.

The "sex boxes" equipped with an alarm button, security guards and safe sex posters, are the latest attempt to control the prostitution industry.

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"Prostitution is a business. We cannot prohibit it, so we want to control it in favor of the sex workers and the population," Michael Herzig, a Zurich social services director who supervises the city's sex workers said. "If we do not control it, organized crime and the pimps will take over."

There are nine boxes and between 40 and 60 prostitutes can work there each day, during the hours of 7 p.m. to 5 a.m. Customers can drive up to the sex workers, negotiate a rate, and then park in one of the boxes to have sex.

Voters approved the $2.6 million project in a referendum last year.

Prostitution is legal in Switzerland providing women have health insurance, are registered with the authorities and are not forced into having sex.

Individual cities have the right to decide what areas prostitutes can operate in. It's a criminal offense for sex workers to conduct business outside these areas, according to Christian Schwarzenegger, professor of criminal law at the University of Zurich.

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It's difficult to tell what sort of impact the sex boxes are going to have, but Professor Schwarzenegger told CNBC that the police need to make sure the rules are enforced if the scheme is to be a success.

"If the police strictly prosecute people who are offering prostitution outside of the boxed area, there is a good chance the prostitutes will move into this safe area, where prostitution is allowed. The clients will then have to follow," he said.

"Another possibility could be that the prostitutes will move to another city where there is no such regulation because most of clients come by car and they live in areas distant from Zurich."

Around 100 prostitutes are believed to work on the streets of Zurich, out of a total of 1,200 officially registered with the city. Others work in massage parlors and bars.

Sex workers will have to pay $43 a year to use the facilities, as well as $5.40 a night in tax. On top of health insurance, this could force sex workers to find areas of the city to work in that are illegal, said Regula Rother who runs a drop-in center for prostitutes.

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"All the prostitutes have to get permission to work at the sex boxes and women who can't get permission might go back home, but they might also try to work somewhere illegal, somewhere we don't know," Rother told CNBC.

More rules to try and control prostitution may not be the answer, Rother said.

"As more regulation comes in and the authorities try to control the industry, it will go into illegal places. It may work for those women who use the sex boxes because it is really safe. But not all of the women want to work there and it is possible that they will go underground."

The sex boxes in Zurich are similar to the German model introduced in Cologne in 2001. According to Cologne's city authorities, the introduction of boxes caused prostitution to disappear from the downtown area, though a red light district still exists south of the city.