A Chinese prostitute who is a victim of human trafficking has been rescued after police swooped on 12 brothels in Oxfordshire.

The woman, rescued from a brothel in Ferry Hinksey Road, Oxford, was one of 18 prostitutes from 12 countries quizzed by police during Operation Pentameter.

Specially trained officers visited 19 premises in the county, finding eight brothels in Oxford, two in Banbury, one in Bicester and one in Abingdon.

Police would not reveal the addresses of the brothels, apart from the one in Ferry Hinksey Road, which was raided on March 30.

On the same day, another Chinese prostitute at the house was taken to hospital suffering from chest pains, an incident caught on camera by the Oxford Mail.

Operation Pentameter was an eight-week national clampdown on people trafficking.

Across the Thames Valley, 75 prostitutes were spoken to in 43 brothels and four women who were believed to have been trafficked were rescued.

Police also seized £8,000 from an address in Oxford in connection with an investigation into a brothel in Buckinghamshire.

Officers posed as clients to gain entry to the suspected brothels.

They did not arrest anyone, but recorded details of clients and managers, for further investigations.

The prostitutes quizzed by police in Oxfordshire were from across the world, including Thailand, China, Malaysia, Kosovo, Lithuania, the Czech Republic, Italy, Spain, Britain and Zimbabwe, as well as the UK.

Thames Valley Police Assistant Chief Constable Francis Habgood, said: "This operation was unique in its approach it is the first time the force has carried out visits, rather than raids and treated prostitutes as potential victims.

"I think the caring attitude demonstrated by the team definitely assisted them in gaining the trust of a very wary community and, crucially, in liberating four women from a life of modern day slavery."

Prostitutes were spoken to in private by a specialist officer.

Police spokeswoman Rachel McQuilliam said: "In this way each woman was assessed for signs that they may have been working at the brothel as a result of being trafficked."

Mr Habgood added: "Even before the eight weeks of visits could begin, there was around two months of research and scoping work which had to be carried out in order to make sure time and resources were used efficiently and in a targeted way."

Oxford city councillor Sajjad Malik, who has campaigned for years to stop prostitution in Oxford, welcomed the police operation, but called for more action to stop kerb crawling in East Oxford.

He said: "I think the outcome of Operation Pentameter is quite good, but there is still more work that needs to be done.

"I have sympathy with the police, they have a hard job to prosecute these people.

"On the other hand prostitutes are still active in Cowley and people want them to stop.

"A man told me recently he was approached by a woman who asked him the time, then asked him, 'do you want any business?' and he found out she was a prostitute."

The women rescued during Operation Pentameter have been put in touch with agencies like the Poppy Scheme, which helps them get accommodation and benefits, and escape the sex trade. Three people were arrested during the operation, but none in Oxfordshire.

In the Reading area, a woman was recalled to prison and another arrested for failing to appear in court. A woman was arrested in Buckinghamshire on suspicion of possession of Class A drugs. She was released on bail.