Detectives visited 18 brothels across London as part of a crackdown on sexual exploitation and modern slavery.
A total of 46 women were spoken to and offered support. Of those, five were identified as potential victims.
A 36-year-old Hungarian man was arrested on suspicion of controlling prostitution on December 3.
He was interviewed at a north London police station and released under investigation pending further enquiries.
Officers from the Met’s Central Specialist Crime Modern Slavery and Child Exploitation Unit carried out welfare visits in Kensington and Chelsea, Westminster, Hounslow, Ealing, Hillingdon, Merton, Newham, Enfield and Haringey.
The women were found to be from the UK, Brazil, Bulgaria, China, Greece, Hungary, Italy, Poland and Romania.
Detective Chief Inspector Helen Barling said: “This operation has been organised to safeguard the most vulnerable, who are often unseen by society.
“Officers offered advice and support to ensure the women are aware they are not alone and have taken action where necessary.
“We know that in many cases females providing sexual services have travelled from overseas, often fleeing poverty, lured by the promise of a well-paid job in the UK.
“However, upon arrival the situation couldn’t be more different. Their exploiters take their ID documents and they end up working in brothels - sometimes forced to.
“They can also end up in debt bondage where they owe money that they will never be able to repay to people they had trusted.
“Physical and mental abuse is common, as are threats of violence against family members at home.
“The public have an important role to play in recognising and reporting modern slavery.
“If you suspect someone may be a victim of modern slavery, report it. You will always be taken seriously. Protection and support is available.”
Every woman was offered support from partner agencies, including The Salvation Army.
Police said there are many victims of modern slavery who the public encounter every day without realising.
As well as being sexually exploited, hundreds are working in construction, domestic servitude, agriculture, cannabis factories, car washes, barbers and nail bars.
Often, they are told police and authorities in the UK are not to be trusted. With limited English, many are unable to seek help, even if they want to.
Anyone who suspects someone is a modern slavery or trafficking victim can call The Salvation Army’s 24-hour confidential helpline on 0800 808 3733, the Modern Slavery Helpline on 08000 121 700, police on 101 or Crimestoppers anonymously on 0800 555 111.
