The BBC's Hugh Schofield: "The report finds no evidence to back up theories of technical failure"

Details of the 500-page report have been obtained by the BBC.

Our Paris Correspondent, Hugh Schofield, says its findings are likely to confirm the view that the main reasons for the crash were that the car was travelling too fast and its driver, Henri Paul, was well over the legal alcohol limit.

No evidence was found to support previous theories that the car's brakes were faulty or that air bags inflated too early, impeding the chauffeur's vision.

Henri Paul: Drunk and speeding

Tests on the Mercedes - which have been conducted over the last 13 months in a police laboratory outside Paris - have been viewed as the biggest piece of the puzzle still missing in the inquiry into Diana's death.

The report containing the test results will be passed to investigating Judge Herve Stephan on 2 November, sources close to the investigation said.

The report is also said to have found that:

• The car was going slower than originally believed - at about 100kmh (62mph) - which is nevertheless twice the legal speed limit.

• The car did indeed have a brush with a Fiat Uno, although it is not clear whether this had any bearing on the crash.

Police have questioned almost 3,000 owners of Fiat Unos but are believed to have long given up hope of finding either the car or the owner.

The high-speed crash that killed the princess, her boyfriend Dodi Fayed and her driver, Henri Paul, and injured bodyguard Trevor Rees-Jones in the summer of 1997 fuelled a wealth of theories about the cause of the tragedy.

Diana: Many theories surround her death

Judge Stephan will now have to decide whether he has enough information to complete his inquiry into the causes of the crash.

Still unclear is the fate of the 10 paparazzi under formal investigation in the crash. It is thought that they will be cleared of manslaughter charges but a few of the photographers may be tried for failing to assist people in danger.

The Mercedes was rented by the Ritz Hotel from the Etoile Limousine company. The Ritz, where Diana and Dodi ate dinner that night, is owned by Dodi's father, Mohamed al-Fayed.

Before he can conclude the inquiry, the judge must look at other elements including a report into the level of carbon in Henri Paul's blood, a report on the exact causes of death of the victims, as well as a suit brought by Mr Rees-Jones against the hotel and the limousine firm claiming they endangered the lives of others by failing to provide a licensed chauffeur.