Six of the people arrested in the UK in connection with a slavery ring have been released on bail.
The men aged 59, 24 and 45 and women aged 23, 59 and 43 were arrested by Avon and Somerset Police yesterday.
A fourth man, aged 63, remains in custody.
The arrests follow the discovery of three men – one in his 30s, one in his 40s and one in his 50s – by police.
The men have all been taken to a place of safety.
Officers had executed a series of warrants as part of Operation Wanderer, an investigation into forced labour and human trafficking.
The operation involved three traveller sites, a business unit and house in South Gloucestershire, and a residential property in Bristol.
Yesterday, police said that two people were arrested in connection with slavery offences, while the five others were detained on suspicion of offences including failing to appear, cannabis production, money laundering and handling stolen goods.
We urge anyone with information that could help our investigation to contact us on 101 or call @CrimestoppersUK 0800 555 111 #OpWanderer— Avon and Somerset Police - #StayHomeSaveLives (@ASPolice) December 8, 2013
A “significant quantity” of cash was found at one address, while a suspected stolen trailer and cannabis plants were seized from a farm in Somerset.
Chief Superintendent Julian Moss, head of CID at Avon and Somerset Police, said the force had launched an investigation into forced labour and human trafficking five weeks ago.
“This is an ongoing and dynamic inquiry; our primary aim is to safeguard and protect vulnerable victims,” Mr Moss said.
“We know from talking with other police forces and charities such as Unseen that victims in such cases are often forced to live and work in poor and unsanitary conditions, sometimes with little or no pay.
“Some of those affected will not view themselves as victims and, even if they do, may have been unable to speak to the police or any other authorities for a variety of reasons.
“To the outside world the fear and intimidation faced by victims of forced labour on a daily basis are difficult to comprehend.”
The force planned the operation with South Gloucestershire Council, the South Gloucestershire NHS Clinical Commissioning Group (CCG), the National Crime Agency (NCA) and specialist charities, including anti-trafficking organisation Unseen, the Red Cross and The Salvation Army.
Special arrangements have been put in place to support the alleged victims with medical treatment, accommodation, employment and welfare, the police said.
The Salvation Army will also be working with the men.
A police spokeswoman said: “Our investigation is ongoing and we would urge anyone with any information to call 101 or Crimestoppers on 0800 555 111.”