Police and law officials have raided German bordellos under suspicion of social security fraud, among others. They have been trying to stop the flat-rate fee system in brothels, arguing that it violates prostitutes' dignity.

While the global recession has hit the financial sector, the export industry, and car companies, it has also been felt in the world's oldest business sector - prostitution.

One such way which has made headlines in Germany is the flat-rate fee system, offered by at least four brothels in Germany, where prostitution is legal.

The Pussy Club chain offers such a flat rate, which entitles customers to unlimited sexual services all day for a one-off entry fee of 70 euros ($100).

But the new discount scheme has triggered a wave of protests, especially in the southwestern state of Baden-Wuerttemberg.

Authorities there are now trying to shut down the brothels, arguing the new pricing plan violates the human dignity of the women working there.

Baden-Wuerttemberg Justice Minister Ulrich Goll told Germany's Der Spiegel magazine that there was a strong enough legal justification for police and authorities to intervene: If you look at the way these brothels advertise, then there's a violation of the human dignity of the prostitutes who work there, he said, adding that authorities were working on a way to stop the brothels from operating the way they do under that current fee system.

On Sunday, police and justice officials searched brothels using the plan in Stuttgart, Heidelberg, Schoenefeld near Berlin and Wuppertal. They say they suspect the bordellos of social security fraud, employing foreign prostitutes without permission and not maintaining hygiene standards.

The brothels' advertising slogan has a simple message: Sex with all women, as long as you want, as often as you want. For 70 euros customers are entitled to all the sex, food and drink they want between 10 am and 4 pm. The evening flat rate rises to 100 euros.

The operator of the Pussy Club brothels, Patricia Floreiu, defended the new pricing scheme, arguing that most customers leave after one or two sessions and that none of the women are forced into the working under the new terms: It simply brings in more customers. Hardly anyone can 'do it' more than twice. So basically the flat rate is mostly for the free beer, she says.

Two of the brothels, in Stuttgart and Heidelberg, were ordered closed after health inspectors said they might spread disease. The raids also targeted franchises in Berlin and the city of Wuppertal, but those brothels remained open.

German police raided about 600 brothels in 13 states Tuesday night targeting human trafficking from West Africa.

The Federal Criminal Police Office said Wednesday that it was interviewing more than 100 women from different West African countries who were forced to work as prostitutes, some of them minors.

Tuesday's raids follow an investigation of several years. Only if we manage to win the trust of victims and persuade them to cooperate with the authorities can we break the cycle of repression, intimidation and dependency, said federal police chief Joerg Ziercke in Wiesbaden.