What Natasha does on the bed in the dingy room with flaking orange paint so shames her she cannot bring herself to use the word. She calls it "so and so" and sells it here from midday to midnight, six days a week.

On a very good day she makes £45. With each 30-minute session earning £2.50 that works out at 18 different men, many drunk, some violent. She tries to forget the very good days.

"I don't want to be with a strange man who wants to kiss your whole body. Some suck you up and leave red marks. It's ugly." Natasha shuddered. "Ugly, ugly, ugly."

Three years ago she won two beauty contests and was runner-up in another two, including Miss Best Legs, on Nicaragua's impoverished Caribbean coast. With dreams of modelling she boarded a bus for the distant capital, Managua.

But Nicaragua has not fully recovered from its 1980s war and remains the second-poorest country in the Americas after Haiti. Economic necessity kills many dreams.

Now 19, she is a veteran of Salvadoreño, a bar and brothel in a tough barrio known as Costa Rica. The days pass in a miasma of beer, sweat and perfume. "I would not wish my worst enemy to be here," she said. "This is the worst thing you can do."

Not quite, it turns out. There is an even worse alternative: doing nothing. Two months ago police raids shut brothels across the city, expelled clients and sent sex workers home. The leftwing Sandinista government billed the crackdown as a socially progressive effort to protect women from exploitation.

The would-be beneficiaries did not see it that way. Their work, however ghastly, was a ticket out of poverty.

Dozens of prostitutes from Salvadoreño led a revolt against what they said was a violation of rights. Emerging from the shadows of their trade, they went public and mounted an unprecedented media campaign to overturn the ban. Astonished by the protests, the authorities relented and within a week the women were back at work.

"It was just before Christmas and we badly needed money for our families," said Carolina Hacks, 23, another worker at Salvadoreño. "But then we always need money, we're the breadwinners for our children and parents."

The Managua-based Central American Health Institute, a non-governmental organisation which funds medical treatment and disease prevention and is known by its Spanish initials ICAS, welcomed the end of the crackdown.

"That sort of repression drives the trade further underground and makes the women less accessible to us," said Zoyla Segura, a health worker. "This protest was something positive because it showed an awareness of their rights."

Profiting from the earnings of prostitution is illegal but authorities have long turned a blind eye to the bars, massage parlours and strip clubs which employ most of the city's estimated 1,500 sex workers.

Salvadoreño, a courtyard of plastic tables where men drink knee-high bottles of beer, has been operating for 35 years. Traders wander in, hawking snacks, baby clothes and pirated DVDs. Everything is for sale, including the waitresses who provide "servicios" in the seven bedrooms adjacent to the bar.

Sex costs £3.25, of which 75p goes to the business and the rest is pocketed by the prostitute, said Marta Lorena, the manager. "We have 25 chicas working here. It's good money for them and for us."

Though she has gained weight from sipping endless sodas Natasha, who did not want her surname published, retains beauty pageant glamour and is the most sought-after chica. Her earnings support her mother, aunt and younger brother in Bluefields, a sleepy, humid town which feels more Jamaican than Nicaraguan. Even on a quiet day she earns more than a doctor or teacher. On Sunday, her day off, she studies banking at a university, but graduation is at least five years away.

The relative privacy of the work is a consolation. "There are bars where you dance naked and you're touched up courtesy of the house." Natasha has declined work at more upmarket brothels which pay more for a session but have a lower turnover.

"For now this is my life," she said, gesturing to the rumpled bed, bare light-bulb and cracked walls. When a client is especially repellent she urges him to hurry up. If one turns violent she shouts and bar staff come to her aid.

"Three years and I'm still not used to it. You can imagine what it was like on my first day. I'd just had one boyfriend before coming here."

By chance last year the ex-boyfriend visited the bar and spotted her. "I was so ashamed. I ran out and cried and cried. I hope never to see him again." Other men from Bluefields have also recognised her.

"I don't care if the whole of my town knows I'm here but not my family, not my mum. I told her I'm married and that my husband gives me the money.

"That's a lie."