A nationwide clampdown on human-trafficking has led to police raids on more than 500 brothels, most of them in residential areas.

Operation Pentameter 2 has detected a significant shift in the nature of the sex trade in Britain.

Once dominated by red-light areas and massage parlours, prostitution is controlled increasingly by organised gangs that bring women into the country and coerce them into sex slavery.

Pentameter has carried out raids on 542 brothels, resulting in more than 300 arrests and the seizure of £400,000 in suspected criminal assets.

A number of women and children have been taken into the care of the Poppy Project, which has extended its operations from London to Yorkshire and the Midlands.

The Home Office intends to publish a new assessment of the scale of human-trafficking later this year. It is accepted widely that the 2003 figure of 4,000 trafficked women in Britain is a serious underestimate.

Vernon Coaker, the Home Office Minister, said: “Trafficking has changed everyone’s perception of what is happening in prostitution. It is nothing less than modern-day slavery and, with its connections to organised crime, it is a priority for the Government and the police service.”

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