More than 500 women are advertised for sex daily on pimping websites in Northern Ireland, with campaigners warning many are "organised, coerced and controlled".
The women are advertised as "independent escorts" offering an extensive list of sex acts and services. However, the reality is much different according to experts.
Ruth Breslin, director of the Sexual Exploitation Research and Policy (SERP) Institute, warned there were "tell tale signs" that the women are being trafficked.
One sex trade survivor said men who use pimping websites do not care if the "women are trafficked or not" and called for the sites to be blocked.
There are four main websites advertising women for sexual services across Northern Ireland- Locanto, Adult Works, Viva Street and Escort Ireland.
Escort Ireland is the largest, with more than 1,000 women being advertised daily across the Republic and Northern Ireland.
It has been in business for over 30 years.
BBC NI has spent months looking through these websites and on average every day there are more than 500 women advertising sexual services.
Ruth Breslin, director of the Sexual Exploitation Research and Policy (SERP) Institute, said "the majority of women we see on these sites are women who are being organised, coerced and controlled and someone else is making money and profiting from them being sold for sex".
Breslin said there are "tell tale signs that these women are being trafficked into the sex trade".
She said: "If you look at their profile they are often very young. They are advertised as new to Ireland or Only in Belfast for a week."
Many women BBC NI has seen being advertised have "very basic English", which experts say is a huge red flag when it comes to spotting trafficking.
Breslin said: "How can they just turn up in this jurisdiction, set themselves up in a website, write a profile, get themselves a local phone number and an address with very basic English? It is very clear they are being organised.
"These women have very little control over the work they do, how many sex buyers they see and who they see."
Many of the adverts BBC News NI has seen encourage the buyers to "rate" their experience out of five stars.
They are asked to rate physical appearance, satisfaction, value for money and overall experience.
Some of the reviews make for uncomfortable reading.
Campaigners argue that these websites are not neutral platforms but "active players" in the exploitation of women in Northern Ireland.
Breslin added: "There are many profiles on these sites that contain indicators of exploitation and trafficking.
"That means there are so many women, especially young women being advertised and organised in the sex trade, they're being controlled in the sex trade.
"They are there because they are being controlled and exploited."
Breslin said "Escort Ireland is a key player" in the sex trade in Northern Ireland and is making "fantastic money advertising women for sale every day, north and south of the border".
The BBC contacted Escort Ireland for comment, but it did not respond.
Such sites are not illegal and the website carries a disclaimer that "the charges are for time and companionship only", adding that "anything else that occurs is a matter of coincidence and choice between consenting adults".
"Every day we see up to 130 women advertised in Northern Ireland on Escort Ireland at any one time," Breslin added.
"Most of these women are very young. They are often young migrant women."
She said the websites are essentially a marketplace where "vulnerable and often exploited women are advertised", adding that "this gives us great cause for concern".
Mia Doring is an author and a sex trade survivor who wants access to these websites blocked.
"We need to disrupt the demand and to send a message to the punters that we are not tolerating what you are doing and what you are doing is committing a crime and we're going to try and interrupt that behaviour," Doring said.
She said: “The men already know that what they are doing is a crime, and they already are full of shame because otherwise why are we not hearing from them?
If they weren’t full of shame and they didn’t think what they were doing was so wrong, why are there no groups of punters fighting for their rights to pay for sex?”
Doring said they are “anonymous and secretive, and they keep it to themselves for a reason. Because they know what they are doing is wrong.”
She added that the men that use these websites are “deeply misogynistic”.
“Prostitution is the most brutal expression of misogyny and we don’t see it as that because it’s kind of couched as work and empowerment.
“But prostitution is the worst form of toxic misogyny that could exist. So, the men act out their brutal fantasies on the women.
“They do not care if the woman is trafficked or not. They know well what they are doing is wrong.”
The legislation making it a criminal offence to pay, either directly or through another person, for sexual services came into effect in Northern Ireland in 2015.
However, it is not illegal to sell sexual services in Northern Ireland, and it is also not a crime to loiter or solicit for the purpose of offering to sell sexual services.
It is, however, a crime to keep or manage a brothel or to control prostitution for profit.