Punters who visit prostitutes are being asked to tell police if they think the women are victims of the sex trafficking trade.

Officers are asking for information as part of Sussex Police's ongoing war against the illegal industry.

Detective Superintendent Russ Whitfield, head of specialist investigations, said: "It's very much a hidden crime and we are trying to change that but we need the help of the public.

"I'm talking about people who have visited sex workers or those who work alongside other sex workers.

"It's the traffickers we are after and the people who have been trafficked who we want to rescue not the 'client' who has inadvertently used a trafficked sex worker.

"If a person has visited a brothel and they feel there was someone who's been trafficked then we want to know about it."

He said victims had been known to pass messages to people visiting brothels and any signs that sex workers are working against their will should be reported.

DS Whitfield was speaking about Sussex Police's involvement in the recently launched Operation Pentameter 2.

It is a national operation by police across the country to tackle human trafficking.

DS Whitfield said it is a growing issue across the country but not a big problem in Sussex.

Features of the latest operation will be to assess the scale of the problem and gather intelligence.

He said offering support for the victims was an important part of their work.

He said: "The issues for the victim are huge. They are in a foreign country often don't speak English and have nowhere to run.

"You can only imagine the horror those people go through and we are appealing for all the support we can to stamp this out."

There have been three cases of sex trafficking in Sussex in the past 12 months and three women have been rescued from brothels.

All the women have been returned to their home countries.

In May 2006, a Lithuanian woman was rescued from a brothel in Brighton.

A woman, Kelly Heath, was convicted of keeping a brothel in October last year and was given a conditional discharge.

In December 2006, a Malaysian woman was rescued from a Hastings brothel and in May this year a Chinese woman was rescued from a brothel in Chichester.

Investigations are continuing in both these cases.

He said the police were working with other agencies to ensure support would be given to anyone who is rescued from brothels in Sussex.

Citylight is a Brighton charity which has been set up, in part, to help look after women who have been rescued from the sex trade.

Samantha Godec, development worker for Citylight, said: "Most trafficked women have put their trust in family or friends.

"In many cases their trust in authority has completely gone."

She said the charity will work with trafficked women to find safe accommodation, legal representation and any other support they might need.