The information given by the MP was "misleading" and a computer check had to be made to determine his identity, Northamptonshire's Chief Constable Chris Fox said.

Mr Ashton has already denied taking part in or paying for sex at the massage parlour and threatened to contact the Police Complaints Authority over the leaking of his name.

The police chief said he was taking steps to investigate how the MP's name became public and would ask him to substantiate his claim the police had been responsible.

The Thai massage parlour raided by police

Any officer shown to have leaked the name to the media would be "dealt with in the strongest possible way".

But he questioned Mr Ashton's statement that the leak must have come from within the ranks of the police.

"Allegations of this kind can be extremely damaging to the force and I have yet to find out why people are so sure that any leaks must have come from Northamptonshire police," he said.

"There were a great many other people with knowledge of this case - defendants, witnesses, legal representatives, other organisations and other individuals."

The raid on the massage parlour in Northampton took place on 26 November. Mr Fox said he had decided to release full details of Mr Ashton's involvement since much of it had already become common knowledge.

His statement said: "When questioned at the weekend about Mr Ashton's presence at the massage parlour during the raid, Northamptonshire police confirmed that one man was present when officers executed their warrant.

"They said he was not committing any offence and that he declined to assist the police as a witness, which he was perfectly entitled to do.

"However, now that it is in the public domain, Northamptonshire police confirm that Mr Ashton was present at the massage parlour when the warrants were executed.

"Since the information recorded by the police was misleading, a computer check was necessary to properly establish his identity.

"He was subsequently interviewed in the presence of his solicitor and declined to give a witness statement."

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In his own statement, Mr Ashton unequivocally blamed the police for the newspaper reports.

He said: "Only they and I and my legal advisers know what happened between the police and myself.

"I did not give inaccurate particulars of my name and address and the reports that I did are misleading. I did not partake in or pay for any sexual services either.