French court officials spent an uncomfortable day today searching for the case file on the death of Diana, Princess of Wales, after a lawyer complained that tens of thousands of original documents had gone missing.

Jean-Louis Pelletier, who represents a photographer prosecuted after the Paris car crash in 1997, claimed earlier today that the file - a metre wide and containing photographs, reports, statements and other evidence - had vanished from the central law courts on the Seine.

After a report in Le Figaro newspaper, embarrassed officials denied that there was any problem and announced this afternoon that they had tracked down the dossier. "We have traced the original file," said a spokesman who denied the documents had been disappeared from the Paris court archives, saying the lawyer's request had instead been misdirected.

The original file was stored in 2002 after the Diana death investigation, led by Judge Hervé Stephan, was wound up after legal challenges by Mohamed Al Fayed, father of Dodi Fayed, the Princess's companion. It has been used in subsequent proceedings.

"I wanted, out of curiosity, to see the original file a month ago," Mr Pelletier told The Times today. "They said it couldn't be found. The appeal court didn't have it. The registrar didn't have it and nor did the law courts' archives. It's very troubling that a file of this importance could disappear. The authorities responsible for keeping it could not tell me where it went."

Several complete photocopies of the case file exist, but the originals are legally necessary for future proceedings, such as the new British inquest that is opening on October 2. The British jury is to visit the Alma tunnel in Paris, the scene of the accident in which the Princess was killed on August 31, 1997.

Judge Stephan's investigation, carried out with Martine Monteil, then chief of the Paris serious crime squad, concluded in September 1999 that the accident was caused by the drunken state of Henri Paul, the driver of the Princess's car. Manslaughter charges against nine photographers and a motorcycle courier who pursued the car were dropped. Mr Al Fayed has never accepted the findings.

While claiming a conspiracy, he continues to pursue three of the photographers for breach of privacy. Fabrice Chassery, Mr Pelletier's client, is one of them. They are appealing to the highest court after appeal judges reversed a lower court acquittal and found that they breached the privacy of the occupants of the crashed Mercedes.

Mr Pelletier is separately pursuing publishers who have printed a picture of the dying Princess, which Mr Chassery took at the scene of the accident. The photographer decided not to distribute the picture when her death was announced. The judge's case file contained originals of all the photographers' pictures on the night of the accident.

A copy of Mr Pelletier's picture began circulating internationally three years ago, becoming the most celebrated image of the Princess's last moments. Mr Pelletier speculated that the pirated picture came from the file. "The photograph could be a copy by someone with access to the file, or stolen along with the whole file," he told The Times.

The report on the file's brief disappearance came as a coroner, Lord Justice Scott Baker, held his last preliminary hearing before the inquest into Diana's death finally opens.

Ian Burnett, QC, counsel for the inquest, used the hearing to outline the logistics and said that the jury - made up of members of the public - would travel to Paris with the coroner and interested parties.

The jury is set to be sworn in on October 2, followed by any opening remarks by Lord Justice Scott Baker. Over the following two days, they will hear scene setting evidence and be given maps and photos, before heading to Paris.

Video link evidence from France is expected to start around October 10, and involve witnesses who saw the Mercedes and the aftermath of the crash, after which it is hoped there will be evidence from the paparazzi.

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