A report says that sex workers in Westminster are at greater risk of violence because of a fall in demand and an increase in those selling sex.
The study by Westminster Council shows the recession has led sex workers to cut their prices, accept more clients and take greater risks.
The police, the NHS, council workers and sex work projects contributed to the report.
It recommends increased training and joint-agency work.
The report says: "Saturation of the market has had the impact of increased competition, meaning some sex workers are now selling sex for less money and providing a wider range of services."
Sex workers interviewed for the report said there had been about a 50% reduction in prices over the last few years.
This has meant many are accepting clients who appear to be more dangerous in order to make enough money.
They are also having to travel further afield to find clients which means it is harder for police and outreach agencies to keep track of them and provide help.
Councillor Ian Rowley, chairman of the task group set up to research sex work in Westminster, said: "The risk of violence has increased substantially."
He said women in particular were taking more risks in a "recession-fuelled environment".
Last July the cross-party task group was set up and sponsored by the Department of Health to tackle rape, sexual assault and violent robbery against sex workers as a public health concern.
Sex tends to be sold in Soho and Paddington, both on the street and by appointment in brothels.
There are about 80 to 100 known brothels in Westminster - the most in London - but the actual number is expected to be higher, the report says.
It highlights the number of women selling sex on their own on the street has "increased considerably" over the last few years, and with it incidents of violence and robbery.
Local sex work projects blamed the closure of brothels in Westminster.
The study found there is a high level of under-reporting to the police, and when sex workers do report violence they do not always receive the help they need.
It makes a number of recommendations, including improved joint-agency work between Westminster City Council, Westminster Police and the NHS, which would cost about £54,000 for one year.