The Serious and Organised Crime Unit of Thames Valley Police carried out the raids as part of its operation against a group which has been operating in Milton Keynes, a town north of London. The gang has been bringing in large quantities of class A drugs such as heroin and cocaine from London to trade on the town's streets.

"This is the largest operation of its type carried out within the Thames Valley," Detective Chief Inspector Darran Hill of Thames Valley Police's Serious and Organised Crime Unit, said. "We have worked with a number of partners who have been key in the success of this operation in order to safeguard vulnerable individuals."

Hill said the "operation has been hugely successful and in total we have safeguarded 36 people who we believe are the victims of modern slavery and human trafficking, made a number of arrests and also seized cash and drugs."

Car washes used as fronts

The gang is believed to have used car washes as a front for its activities with individuals who police believe may have been trafficked into Milton Keynes as modern slaves. Four car washes were raided in Milton Keynes and one in the nearby town of Bedford.

Thames Valley Police Detective Chief Inspector Nicole Murphy said: "Officers have executed a number of warrants in Milton Keynes in both car washes and residential properties. Using what appeared to be legitimate businesses, in this case car washes, we believe this to be the front for people smuggling and drug dealing."

The victims were "safeguarded" and are being cared for by police partner agencies and charities.

Police also raided 20 residential addresses.

Cocaine, cannabis, thousands of pounds in cash and a Mercedes ML 250 car were also seized.

Thirteen people were arrested on suspicion of offenses including modern slavery, people trafficking, conspiracy to supply class A drugs and immigration charges.

Murphy said authorities were "working to dismantle a potential people smuggling network."

Cooperation and appeal

UK authorities worked with Belgian federal police to safeguard a further six victims, including a 16-year-old and 17-year-old boy. Police also arrested a further two individuals for human trafficking offenses.

Britain's crime agency last month launched an appeal to tackle modern-day slavery, urging people to report suspicious activity: "In order to tackle serious and organized crime we need the public's help and support," Murphy said. "We would ask anyone who thinks someone is being exploited to please report it."

"Some of the common signs of modern slavery and exploitation can be found on our Hidden Harm page."

The last major study by the UK government into the scale of modern slavery was produced by the Home Office in 2014: "The estimate suggested that there were between 10,000 and 13,000 potential victims of modern slavery in the UK in 2013." Worldwide, the figures are in the millions.

jm/kms (AFP)