MONTREAL - Bright neon signs that simply read 'massage' have become a fixture in Montreal in the past decade, but while they bill themselves as legitimate businesses, what happens behind closed doors is anything but.

Many massage parlours -- not to be mistaken for legitimate therapeutic clinics -- are now brothels, and they have sprouted up in almost every neighbourhood.

An undercover operation by CTV Montreal visited a dozen massage parlours chosen at random. In all but two, our reporter was offered the chance to buy sexual acts for as little as $20.

Diane Matte and her group CLES (Against Sexual Exploitation) have been tracking the explosion in the number of massage parlours in Montreal as part of their work to fight sexual exploitation.

"It's like the new brothels really," said Matte. "There's 200 of them in Montreal alone" that advertise.

Many are open 24 hours, and many advertise online.

Operating unchecked, they only require the same permit as a hair salon.

"It's clear that it has become almost trendy. You know, no one is questioning the idea that men can go to a massage parlour and buy sex acts," said Matte.

Teenaged girls frequently working as prostitutes

What's openly marketed as harmless stress relief for men, and a private transaction between consenting adults, is sometimes anything but.

CTV Montreal talked to several ex-prostitutes who worked in massage parlours.

Jenny (not her real name), was an adult when she worked in six different erotic massage parlours, and she says there were definitely underage girls having sex with johns.

"I've seen 15, 16, 17 year-olds," she said.

"Men are looking for young women," said Matte. "They're looking for the youngest and the industry is providing the youngest."

The Missing Children's Network says runaway girls are especially easy prey for the sex trade.

"By the time they realize that they were groomed for sexual exploitation purposes it's too late for a lot of these young girls," said Pina Arcamone.

Montreal police Commander Ian Nantuoni says that ever year, police investigate up to 150 cases of underage girls working as prostitutes, including in massage parlours.

"[Pimps] target people who are vulnerable girls that have either problems at home or at school or that they're looking for love or affection," said Nantuoni.

Another prostitute, Noemi (not her real name), was a 13-year-old runaway when a pimp lured her into prostituting herself in the back room of a strip club.

"Worst experience of my life," said Noemi, who was paid in drugs.

A year later another pimp tried to get her into a massage parlour.

"At first, I felt like a princess. They bought everything for me. They were paying to do my nails, my hair, tanning salon, and clothes," said Noemi.

Then they told her she would be moved to Ontario

"You can't just stop whenever you want. You don't decide at that point . You have no control," said Noemi, who ended up returning to her group home.

Victims of human trafficking

Women are not just taken across provincial borders to work in massage parlours.

Police say young women from other countries are being brought to Montreal and sexually exploited.

"There is human trafficking," said Annie Robert. "It is happening in massage parlours.

In one case a young Chinese woman was lured to Montreal thinking she'd get an education. She ended up giving erotic massages to pay for her flight and room and board.

"She did forced labour and also she has been exploited sexually," said Robert.

"In Asian salons, often you'll see 15 Asian girls and one or two from Quebec," said Jenny. "They're all in a small room. Controlled and scared, these girls didn't speak French or English, all sitting on a mattress. It's not the nicest image I've seen."

Part Two of this series looks at efforts to stop sexual exploitation, and what girls need to know to avoid being lured into the sex trade. It airs Tuesday at 12 and 6 p.m.