The research, led by Dr Nick Mai, said many migrants preferred to work in the sex industry rather than in “unrewarding and sometimes exploitative conditions they meet in non-sexual jobs”.

The report also discovered that many migrants working in the sex industry sent money back home, for “dramatically improving the living conditions of their families”.

Dr Mai discovered – from 100 male, female and transgender interviewees – that 13 per cent felt they had been exploited and 6 per cent believed they had been “deceived and forced” into prostitution.

Although human trafficking is still a problem for hundreds of people, the research showed it is not as large as it is believed.

Dr Mai said: “The perception that the sex industry is connected to international organised crime has raised moral panic about trafficking.

“Neither the moral panic, nor legislation brought in to counter trafficking, reflects existing research evidence.”

The survey found that 96 percent of London’s sex workers were migrants.

The report adds: “The evidence strongly suggests that current attempts to curb trafficking and exploitation by criminalising clients and closing down commercial sex establishments will not be effective because as a result the sex industry will be pushed further underground.

“People working in it will be further marginalised and vulnerable to exploitation.”

A survey in 2000 said that 10 per cent of UK men have paid for sex.