A 42-year-old woman from Penhow has been arrested as part of a slavery investigation by Gwent Police.

More than 100 officers and staff were involved in the execution of three warrants at addresses in Penhow, Cardiff and the Marshfield area of Newport.

A 66-year-old man and a 42-year-old, both from the Marshfield area, and a 36-year-old man from the Cardiff area have also been arrested.

The investigation began when a 43-year-old man was found to be living at the Marshfield site in very poor conditions having been reported missing by his family 13 years ago.

Officers also believe a body may be buried at the Marshfield site.

A specialist team of detectives has been investigating and gathering intelligence to ascertain whether this part of a larger criminal conspiracy.

Uniform officers and detectives from Gwent Police, working with other specialist units including members of the dog section, air support unit, and the armed response unit have entered premises in relation to offences regarding Slavery and Servitude from the Criminal Law Act 1977 and the Coroners and Justice Act 2009.

The four arrested are in police custody assisting officers with their enquiries.

A dedicated team of detectives has been responsible for the bringing the long-running investigation to this latest phase, which has centred around evidence and intelligence suggesting that people were being kept in poor conditions at the Marshfield site and forced to work for no pay.

A man has been taken from the Marshfield site to an undisclosed medical reception centre, where his physical and mental condition can be assessed and by specialist staff.

The man, whose age is unknown at this time, is of eastern European origin.

Detective Superintendent Paul Griffiths, who is leading the investigation, which is known as Operation Imperial, said: "Today's action is the latest phase of a long running investigation into alleged offences of Slavery and Servitude.

"In addition to the suspected offences in relation to Slavery and Servitude, we are also acting on intelligence which suggests that the body of an unknown person may be buried at the Marshfield site.

"As such specially trained officers, equipment and a forensic archaeologist have been deployed to investigate this.

"Because of the scale of the investigation we are fully aware the operation has caused disruption to other residents, especially in the Marshfield area, and we thank them for their continued co-operation and understanding.

"The offences that are being investigated are extremely serious and we would urge anyone with any information which could assist the team to contact Gwent Police on 101 quoting log 66 23/09/13.

"Alternatively if someone has information and would rather not pass this directly to the police then I would urge them to contact Crimestoppers, which is independent of the police and guarantees complete anonymity, on 0800 555 111.

"They don't need to give their name and the police will never know who they are. Any information given would be passed to the team in complete confidence."

Gwent Police is working in conjunction with Serious Organised Crime Agency (SOCA), other Forces, UK Human Trafficking Centre, RSPCA and the Red Cross.