A man and a woman have been arrested in Bristol as part of a investigation into the trafficking and exploitation of dozens of Slovak migrants.
A Slovakian man, 43, and a Polish woman, 44, have been held on suspicion of Modern Slavery Act offences, money laundering and fraud.
It follows a two-year investigation by the National Crime Agency (NCA).
The agency said victims would be threatened with violence, have wages withheld and bank accounts controlled.
The pair were arrested in the Fishponds and Locklease areas of the city on Tuesday.
It follows allegations of dozens of mainly Slovak migrants being transported to the UK and put to work in labouring jobs or car washes.
The investigation was supported by Avon and Somerset and Slovakian police
Ian Glover, of the NCA, said it was a “major step” in what had been a “long and complex investigation”.
“Throughout we have heard distressing allegations of the exploitation, abuse and humiliation of victims for financial profit,” he said.
“Those victims have now been safeguarded and are being supported.”