Human trafficking is a developing crime in Northern Ireland, police said.
Between April and December last year, 15 victims of human trafficking were rescued and four people were charged.
Huge sums of money are being poured into the industry, with vulnerable foreign nationals used as slaves.
The Blue Blindfold campaign, a cross-border initiative aimed at raising awareness of the evil trade, has now been launched.
Detective Chief Superintendent Roy McComb, head of the organised crime branch, said: "We very much see this as a crime that is developing in Northern Ireland. It is a worrying trend. This is about the exploitation of human beings. We need to be strong that we don't want this in Northern Ireland."
He added that the public needed to be on the lookout for rented accommodation with people coming and going at all hours of the night. "They are being treated as no more than labour commodities," he warned.
He said the trade was increasingly of concern to police. "We have a greater understanding of the nature of the crime. We are keen to get as much information as possible."
Northern Ireland Justice Minister David Ford launched the campaign. "It is difficult to accept that this form of modern day slavery is happening in Northern Ireland," he said. "I hope this campaign helps to open eyes to this heinous crime and that people realise it could be happening in a location near them."
The Blue Blindfold campaign will run in Northern Ireland for the next three months, while Irish Justice Minister Dermot Ahern has begun a public information campaign.
Mr Ahern said: "The trafficking of human beings for sexual and/or labour exploitation or the removal of organs is a most serious offence that has no place across the island of Ireland. We are very committed to taking a strong approach to jointly combating this crime and urge all members of the public to assist us in this task."