Oxford County Court has tightened its security procedures after a member of staff mistakenly sent sensitive medical information and National Insurance numbers to a woman trying to settle her parking fines.

Emma Kelly said she was worried identity fraudsters could have capitalised on the error, which saw a form containing highly confidential information about nine people sent to her.

Over the weekend the Oxford Mail used the information to trace one of the individuals listed on the document.

Miss Kelly received the sheet on Thursday at her home in Barton Lane, Headington, Oxford.

It was sent in a plain envelope with a letter about her attempt to delay a warrant, which would enable bailiffs to collect property as payment towards £267.81 in parking fines accrued at the John Radcliffe Hospital, where she works.

Her Majesty's Court Service said the blunder was the result of an "administrative error".

The A4 sheet - which bears no relation to the documents concerning Miss Kelly's court proceedings - contained the names of what appears to be nine NHS patients, their respective National Insurance numbers, and the medical wards in which they were treated.

Information on the document sent by the court in St Aldate's also included a list of court orders for fines against the people on the list and handwritten reference numbers - including one for the Child Support Agency.

Miss Kelly, 22, said: "I am a bit angry considering how much information about these people it has got on it.

"I am a little bit worried it is only page three of four. Where are the rest of them?

"My name could be on one that someone else has got. It could be used for identity fraud."

The security lapse follows an embarrassing blunder by HMRC, which saw two compact discs with names, addresses, bank details and National Insurance numbers for 25 million people go missing in November.

Miss Kelly said: "If the Government have already lost tens of thousands of peoples details, you would think other people dealing with the same details would be more careful about what they are doing."

A spokesman for HMCS could not confirm what the form was used for or where the other three pages of documents were.

A statement said: "HMCS takes this matter extremely seriously and constantly reviews all processes to ensure the safe transfer of data throughout its systems.

"The data concerned was sent following an administrative error. Processes have been tightened to prevent this incident happening again."