New Zealand sex workers are furious that foreign prostitutes who come on temporary visas can advertise their services here despite it being illegal for them to work.

High profile escort Lisa Lewis is one of several who have taken their complaints to Immigration New Zealand (INZ) and the Minister of Immigration Iain Lees-Galloway - calling for a harsher stance against migrant sex workers.

Although prostitution is decriminalised, it is illegal for temporary migrants, such as those on student or work visas, to provide sexual services in New Zealand.

"There are laws in place regarding who can and cannot work as a prostitute in New Zealand," Lewis said.

"But why is there no questions being asked when migrant sex workers advertise their services on websites and the back pages of newspapers here."

She wants INZ to shift its focus from just deporting migrant sex workers to punish those that profit from helping the promotion of these illegal sex workers.

Lewis said the increase in number of foreign prostitutes coming over has hit local sex workers in the pocket.

"Many of the girls no longer meet the same quota as they did a few years ago," she said.

These foreign girls were also offering services such as "natural" acts or unprotected sex, Lewis said, which is unlawful under prostitution laws here.

"These not only put their health and safety at risk, but also clients' health and safety at risk," she said.

Lewis, who has been involved in sex work for the last 10 years, said she has seen the number of advertisements by migrant prostitutes more than double over that time.

An advertisement by a sex worker in New Zealand. (Photo / Supplied)

Some advertisements openly declare that the sex workers had "just arrived" or "here for a short time" along with their foreign nationalities. Others openly say they offer specials like "natural" sex acts.

Another sex worker, who spoke to the Herald on the condition of anonymity, said her income had halved from about $12,000 weekly to about $6000 in the last two years.

In 2015, a 27-year-old Korean sex worker who came to New Zealand and was caught by police after working for 20 days was found to have earned $32,875 over that time.

Police found she had 196 customers and charged up to $100 extra for special services, including unprotected sex.

"We can't compete with the type of services they offer, and besides it is illegal for us to do so," she said.

"But the fact is, every dollar that these migrant prostitutes make is a dollar taken from the back pockets of New Zealand working girls."

The Auckland-based sex worker is hoping the complaints will lead to stronger enforcement of the laws.

"The laws are there for a reason. What's the point of having them if they are not being policed," she added.

Amber Ohara, a sex worker from Christchurch, is calling for a sex worker registration system similar to the one in Victoria, Australia.

"There every sex worker must have a registration number showing on her advertisement or the advertiser gets fined," Ohara said.

"This would wipe out large numbers of the illegal ladies overnight."

INZ has received eight complaints in relation to migrants using the services of websites, including newzealandgirls.co.nz.

"The nature of the complaints were in relation to allegations that migrants were using these and other websites to advertise their services," said INZ spokeswoman Emma Murphy.

Murphy said the complaints had been made anonymously.

INZ said no investigation had been undertaken as a result of these allegations as there was "insufficient evidence to warrant further immigration action".

The Herald has approached newzealandgirls.co.nz for comments.