By Navdip Dhariwal BBC correspondent in Bombay

The chance to see a Bollywood-style dance attracts many men

For these girls, looking pretty is essential to earning a good wage.

Kalpana came to work as a dancer at one of the beer bars in Bombay (Mumbai) - but it wasn't her dance skills the bosses were interested in.

"They told us to dress up good... they didn't see our dance," she recalls. "They just tell us - dress up well and pay attention to the customer. First of all, it's our job to entertain them..."

Swirling sequined skirts and young faces entice their audience.

These are mostly middle-aged men, delighting in a private Bollywood moment of their own.

They can look but they can't touch.

But the girls aren't interested in the men, as much as in the wads of cash they wave at them, or shower over them, as they move to the music.

Entertainment or exploitation?

Bombay columnist Rohit Gupta spent three months visiting some of the city's 2,000 beer bars.

He uncovered the whole spectrum of bar culture, ranging from the high-class and corporate to the seedy and sinister.

Sequins and sashaying hips greet customers to the bar

"In [some places] you can actually call them and they sit down with you, for a tenner maybe," says Mr Gupta.

"You can talk to them, chat with them. The bar is attached to a hotel... [so] it's a bar as well as a brothel."

Beer bars are not illegal, but some of them act as a front for prostitution. It's a thriving industry, which brings together bar owners, hoteliers and traffickers.

If the bars are raided by the police, the penalties are far smaller than they would be for a brothel.

And the girls have been taught how to react to a raid.

"We have to run and hide somewhere and when they go, we can come back, change and go home," says Kalpana.

Family problems

On the outskirts of the city is a refuge for young girls rescued from prostitution.

Some of them are as young as 14.

Although most of the girls were in brothels, Balkrishna, who works at the refuge, is concerned that bars are becoming a new trafficking point for young women.

The girls say their employers make sure they come to no harm

"We have lot of girls who were trafficked and sent to beer bars," he says. "This is a different type of prostitution."

At this bar, the girls say they do no more than dance.

Their safety and welfare is looked after by the men that employ them.

"There are regular customers. They are very friendly to us - they don't say anything, they are really good. They just come here for entertainment - to drink and go home."

But ask them if they choose to work here, and their eyes become downcast with shame and sadness.

"I wanted to become a customs officer," says Kalpana. "But because of some family problems and financial problems, I had to come here."