Each wooden facility will be equipped with a panic button for use in emergencies, as well as posters giving advice on safer sex

Sex workers in Zurich are to be given access to purpose-built drive-in wooden booths as part of a £1.5 million plan to clean up the city's red-light industry.

Nine garage-style "sex boxes" will open this month in an industrial zone in the west of the city, and will be accessible to sex workers and their customers from early evening until 5am.

Under the plan, men wishing to pay for sex will have to drive through a checkpoint before selecting from a line of 40 prostitutes.

Punters will then have access to one of the wooden units, which are each equipped with panic alarms and contain posters promoting safer sex.

Sex workers will have to buy a £3.50 nightly "work ticket" to gain access to the booths, as well as registering with a health insurer. Pedestrians or motorcyclists are not allowed.

The "sex box" facilities are one of several measures aimed at reducing the number of prostitutes plying their trade in residential areas and the city centre, including a ban on soliciting along the Sihlquai river embankment.

Men who solicit street workers outside three approved zones, including the sex box facilities, will be liable for a £310 fine.

Welfare department official Michael Herzig said: "We want to regulate prostitution because until now it was the law of the jungle.

"It was the pimps who decided the prices, for instance. We are trying to reach a situation which is better for the prostitutes themselves, for their health and security and also for people who live in Zurich."

Prostitution is legal in Switzerland, while the sex-box plan received overwhelming backing from residents in a poll in March last year.