The inquest into Princess Diana's death in a Paris car crash 10 years ago opened on Tuesday with accusations that the British royal family ordered her death.

Mohamed Al Fayed, whose son Dodi also died in the crash after a brief but high-profile summer romance with Diana, said the couple were killed on the orders of Queen Elizabeth's husband, Diana's former father-in-law.

In a string of accusations listed in court by the judge, the owner of London's luxury Harrods store said the royal family could not bear the idea of Diana marrying a Muslim.

Major investigations by French and British police have concluded the deaths were a tragic accident caused by a speeding chauffeur, who was found to be drunk. They both have rejected Fayed's conspiracy theories.

Lord Justice Scott Baker said Fayed alleged in a prepared witness statement that the royal family "could not accept that an Egyptian Muslim could eventually be stepfather to the future King of England (Diana's elder son Prince William)".

"It's his belief that a decision was taken to kill both Diana and Dodi. He places Prince Philip at the heart of the conspiracy."

The judge told the jury: "You will have to listen carefully to the witnesses you hear to see whether there is any evidence to support this assertion."

Diana, 36, Dodi Al Fayed, 42, and chauffeur Henri Paul were killed when their Mercedes car crashed in a road tunnel as they sped away from the Ritz Hotel in Paris, pursued by paparazzi.

Fayed said Diana was pregnant with Dodi's child and that the couple were planning to announce their engagement.

The Egyptian-born tycoon alleged that US, French and British security services had bugged Diana's phone and knew about the couple's plans.

He suggested the couple were killed after a blinding flash from a stun gun distracted Paul, who crashed at speed after their limousine was dealt a glancing blow by a white Fiat Uno.

He also said Diana's body was hastily embalmed to disguise the fact that she was pregnant.

The judge said Diana had spoken to both her lawyer and  butler about her fears of being killed in a car crash.

Fayed fought a long legal battle to have the inquest heard by a judge and jury. London's High Court is expected to spend up to six months deciding if her death was an accident.

Britain had to wait for the French legal process to end and then for the British police investigation to run its course before the inquests into Diana's and Fayed's deaths could begin.

Up to 140 reporters from around the world have been accredited to attend the court and the jury have been promised police protection from the glare of media publicity.

Under British law, an inquest is needed to determine the cause of death when someone dies unnaturally.

Scott Baker told the jury of six women and five men to ignore the "literally millions" of words written about the crash, much of which had shown a "disregard for the facts".

He will be flying with them to Paris next week so they can see the crash scene. Reuters