The rescue of a number of people following raids on a series of suspected brothels in Belfast may just be the tip of the iceberg of the true scale of human trafficking in Northern Ireland.

Fifteen people — 12 women and three men — were rescued yesterday during a a major UK-wide operation involving officers from the PSNI’s Organised Crime Branch to assist victims of organised crime gangs involved in human trafficking.

Police have not revealed how many alleged victims were rescued in Northern Ireland.

Four people were arrested during the searches of 15 properties across the UK and they will be questioned here.

Detective Chief Superintendent Roy McComb, head of the PSNI Organised Crime Branch, said: “Dealing with human trafficking and the exploitation of vulnerable people is a high priority for the PSNI, and (the) operation shows our continuing commitment to pursue anyone involved in such crimes.”

He added: “Human trafficking and prostitution is no longer gender specific. Men and women are being tricked or forced into prostitution in major towns and cities. They are being robbed of their liberty, stripped of their dignity, and suffer intolerable conditions as unwilling emblems of the sex trade.

“This is modern day slavery where human beings are treated like commodities by organised crime gangs who are making substantial criminal profits from the sex trade. These gangs have no thought for the health and well-being of their victims. They see them simply as instruments to help them generate cash.”

SDLP Assembly Member Dolores Kelly said she is concerned that this may just be “the tip of the iceberg”. “It is a most foul activity in terms of preying on the most vulnerable people. Many of these women and men have come here, dreaming or promised a better way of life and have been subjected to the most cruel and psychologically disturbing conditions,” she added.

Patrick Yu, executive director of the Northern Ireland Council for Ethnic Minorities, said the discovery was welcome but warned the women needed protection.

“In most cases they don't want to testify (against their captors) because their family may be in danger at home,” he said.

Patricia Lyness, a project manager at the Women's Aid Federation, said the authorities had made an effort to improve their handling of the trafficked women.

“I think really both the Department of Justice, who have responsibility for it, and the PSNI are working very hard to provide support to the victims,” she said.

Alliance MLA Anna Lo said that, just a couple of years ago, the NIO stated that there was not a big problem of human trafficking in Northern Ireland.

“But it is clear that this crime is quite widespread. This is a sickening crime carried out by callous individuals who see no moral problem in buying and selling human beings. These people must be stopped before more victims are forced into what amounts to 21st century slavery,” she added.