Westminter is the centre of London's illicit sex trade, a shocking new report into the capital's brothels has revealed.

The borough houses at least 71 brothels, the highest number in the city according to researchers who posed as punters from the Poppy Project, a support charity for women who have been trafficked for sex.

A total of 921 brothels were found across London, but Westminster has more than twice the average number as men flock to the West End looking for cheap sex.

The report - Big Brothel - found sex was being sold for as little as £15 in a number of private premises including businesses trading as legitimate massage parlours or saunas, and flats.

The Poppy Project, which is part of Eaves charity, says the average age of the women involved was 21 with an overall age range between 18 and 55.

The study also indicates London is a centre of the human trafficking trade with women from 77 countries found in the brothels surveyed.

Over half were European with nearly a third from Asia.

Helen Atkins, who co-wrote the report, said the brothels seen are the tip of the iceberg.

"It's been said you're never more than six feet away from a rat in London - something similar applies to brothels, places where thousands of women are regularly exploited by men who buy sex," she added.

"For most women involved in prostitution the reality is a cycle of violence and coercion, perpetuated by poverty and inequality."

Westminster Council acknowledges the problem and closes down brothels where they come to light, but its focus is on tackling on-street prostitution.