You might think selling young girls and forcing them into the sex trade only happens in places like Asia or Eastern Europe, but 1 NEWS has learnt Kiwi girls as young as nine are being forced to sell their bodies in ordinary houses on our streets.

Wellington researcher Natalie Thorburn says child sex trafficking is disgusting with "adults setting kids up to be repeatedly raped and making money from it".

Ms Thorburn has spoken to dozens of young Kiwi women forced into prostitution.

"It was excruciating to listen to. They were ashamed. They were deeply traumatised," she said.

She says the majority of the girls were exploited from the ages of 12 to 13 but one counsellor, Tania Blomfield, says she knows of one nine-year-old girl who was tied to a bed by her mother after school and forced to provide sex for men.

Ms Thorburn says what is most disturbing is that the majority of people trafficking these youngsters are their families or "boyfriends".

"For some of them it was their parents who were selling them for drugs, who were inviting men over to the house to have sex with the girls and then reaping the benefits of that financially," Ms Thorburn said.

"For most of them it was a boyfriend figure, often gang-connected, who would pose as a love interest and then force them to go out onto the street using violence or the threat of violence and force them to sell sex with others." She calls this the "love illusion".

Ms Thorburn says the majority of clients are white collared businessmen who are increasingly seeking out younger and younger girls.

Tania Blomfield says child sex trafficking is "a growth industry, sadly. I think it's getting worse and worse because we are not dealing with it".

"New Zealand is repeatedly refusing to see it or label it or acknowledge it for what it actually is, which is trafficking," Ms Thorburn said.

She would like to see some specific policy focussing on this disturbing issue.

Both New Zealand Police and the Ministry for Vulnerable Children, Oranga Tamariki, say they do have teams working with underage sex workers.