An enterprising association of sex workers in Barcelona has angered some of Spain's most prominent feminists by offering an "intro to prostitution" course in response to what its members say is a growing number of women turning to sex work in the wake of Spain's financial crisis.

At a cost of €45 (£37) a person, the four-hour intensive course for aspiring sex workers was held last month by the Asociación de Profesionales del Sexo, a group of eight sex workers who lobby for better rights for those in the industry.

All professionals need some training, explained course organiser Conxa Borrell, and sex work is no different. "This isn't an easy profession. There is no other line of work in which you share such intimacy with someone," she said.

The group's efforts to normalise the profession have raised eyebrows before, such as last year's sold-out "sex for women as taught by prostitutes" workshop.

Seven years as a sex worker have convinced Borrell that such courses can play a vital role in setting standards that could help professionalise the industry. "Media often portrays us as a piece of meat with eyes and three holes. It's absolutely false."

The course attracted 15 women from 22 to 50, said Borrell. Attendees included those who were considering the idea and others who had recently started in the industry and wanted more information.

Four hours was too little time, she said, to cover a list of topics such as dealing with the stigma of prostitution, sex tricks, filing tax returns and marketing. A second day will be held this month because of high demand. "Nobody else can teach these things," said Borrell. "Not psychologists, anthropologists or political scientists – only prostitutes."

While no statistics exist to back the group's claim, Borrell said the course was spurred by the rising number of women becoming sex workers during Spain's economic crisis.

"We're at an impasse where people are unemployed, and they still have to pay their mortgages and feed their children," she said. "This is a line of work that many women feel they can do."

In 2007, after her husband's business went under, Borrell found herself in the same situation. One night as she was washing dishes, she heard a news story mention some sex workers in Spain were making €200 a day, and decided to try it out. "I knew absolutely nothing about it," she said. "I didn't know where to take my clients, I had no idea where to meet them. I didn't know how much to charge them."

Some of Spain's most prominent feminists are to meet politicians this week to discuss their concerns, said Lidia Falcón, founder of the Partido Feminista de España. "We want to know if the association holding the course is receiving any public funds. And we want to know if our politicians agree that prostitution should be promoted as an alternative to unemployment."

As in many countries, the issue of prostitution has polarised Spain's feminist community, with groups torn as to whether it should be legal or not, said Falcón. Prostitution in Spain exists in a sort of legal limbo; while not illegal, it is not regulated in any way. Authorities in Barcelona have introduced fines for clients and sex workers working on the street, and Madrid is planning to do the same.

A 2007 parliamentary report on prostitution – the latest figures available for the sector – estimated that there were about 400,000 sex workers in Spain in an industry that generated €50m a day.

Falcón has spent years fighting to have prostitution made illegal in Spain. "Now the last straw is that a group is giving courses to women to become prostitutes," she said.

The problem with the course lies in its underlying suggestion that some women are working in the profession out of their own free will, Falcón said. "It's a false, repugnant discussion about liberty, as if being a prostitute is something you can choose to do because you like it. They say they're helping women, but they're just helping them to be exploited and humiliated."

That feminist groups would be their toughest opposition has surprised Cristina Garaizábal, a psychologist with 30 years of experience who helped Borrell teach last month's course. "They complain that women are being victimised, but then they're against any effort by prostitutes to increase their autonomy and decision-making power," said Garaizábal.

She rejected the attempt by feminists to compare course attendees and women who were being forced into prostitution. "You can't put them all in the same bag. Women who are being trafficked absolutely didn't not come to this course," Garaizábal said. "The only thing that this course is doing is empowering women who are already interested in working in the sector."