LONDON -- Amid incredible accusations of a royal plot to murder Diana, the coroner investigating her death appointed Britain's best-known police chief yesterday to explore the circumstances of the car crash in Paris that killed the Princess of Wales. Royal coroner Michael Burgess opened separate inquests into the deaths six years ago of Diana and her companion Dodi Fayed with brief 30-minute statements explaining how he will proceed before adjourning the hearings for at least a year.

But as he left the inquiry into his son's death, Egyptian-born billionaire Mohammed al Fayed made it clear he has made up his mind what happened, saying the couple were the victims of "absolutely black and white, horrendous murder."

Al Fayed's outburst was fuelled by a letter published yesterday in the Daily Mirror allegedly written by Diana in the months before her death claiming that Prince Charles was planning to have her killed in a car accident to clear the way for him to remarry.

In the handwritten letter on Kensington Palace stationery, Diana writes that Charles "is planning 'an accident' in my car, brake failure and serious head injury in order to make the path clear for him to marry."

The newspaper said the letter, which it published a photograph of with the words "my husband" blanked out before Diana makes her sensational claim, was in the possession of her former butler, Paul Burrell. It said he has been ordered to hand it over to the coroner's inquest.

Burgess said until he reconvenes his inquest in 12 to 15 months, a team of British police officers led by Sir John Stevens, the head of Scotland Yard, will conduct their own inquiries into the crash, which French officials concluded was an accident.

"I am aware that there is speculation that these deaths were not the result of a sad, but relatively straightforward, road accident in Paris," said Burgess, adding the results of the police inquiries will determine the scope of his inquest.

Under English law, a coroner's inquest must be held when an unnatural or violent death occurs abroad and the body is brought back to England or Wales for burial.

The hearing into Diana's death was held in a makeshift court in a large convention room at the Queen Elizabeth II Conference Centre in London.

The room can accommodate more than 400 people but was about a third full.

Burgess said his investigation of the deaths of Diana and Fayed, which could be combined into one inquest, will be driven by the evidence uncovered by French and British authorities.

"I have to separate fact from fiction and speculation," he said. "Speculation and speculative reports are not themselves evidence, however frequently and authoritatively they may be published, broadcast or repeated."

Clarence House, Prince Charles's official residence, had no comment on the allegations but said the prince and sons William and Harry "are very pleased that the inquest is finally underway."

Others, including the paper's own royal watcher, roundly dismissed the letter as a fantasy that revealed more about Diana's state of mind than the truth.

"I do not believe for one moment that the Prince of Wales would ever wish any harm to the mother of his children, let alone be the architect of any move to harm her," James Whitaker wrote in the Mirror.

"We don't live in medieval times when bumping off troublesome spouses, courtiers or mere irritants was part and parcel of royal behaviour."

A French investigation ruled that the car crash in an underpass in central Paris was an accident caused by driver Henri Paul.