LONDON, Jan 7: Six years after her death, Princess Diana still haunts Britain's royal family from the grave - but even close allies dismissed her suspicion that Prince Charles was plotting to kill her.

For her former husband and their two sons, the agony shows no sign of fading. For the conspiracy theorists, there is no smoke without fire. From Scandinavia to Japan, photographers descended on London for an inquest on Tuesday into Diana's death in a Paris road crash in August 1997 with paparazzi in hot pursuit.

What made Diana front-page news yet again around the world was not just the opening of the inquest but a tabloid newspaper naming Charles as the person she suspected of plotting to kill her.

Royal coroner Michael Burgess began the inquest by saying Britain's top police officer should investigate allegations her death was not an accident but a deliberate plot.

Diana made the plot allegation in a letter she gave to her butler and confidant, Paul Burrell, before she died. The Daily Mirror tabloid quoted Diana as saying in the letter written 10 months before her death: "My husband is planning 'an accident' in my car, brake failure and serious head injury."

Diana died at the age of 36, along with her lover Dodi al Fayed and their chauffeur Henri Paul, in the August 1997 crash. Dodi's father, London store magnate Muhammad al Fayed, has long alleged the couple were murdered by British secret services because their relationship was embarrassing the House of Windsor.

"It is absolute black and white horrendous murder," he said after a separate inquest into his son's death. Royal commentators reflected sadly on what they saw as Diana's paranoia in the last year of her life. Few gave any credence to her reported suspicions.

Diana's former sister-in-law and a man who was her royal bodyguard for six years both scoffed at conspiracy speculation stirred up by the letter. "I'm deeply shocked... The tabloids have gone too far," said Sarah Ferguson, former wife of Charles's brother Prince Andrew.

"It's disgraceful. I will not even discuss it. It's absolutely outrageous. I've never been more shocked... it just doesn't do her boys (Princes William and Harry) any good."

Former royal protection officer Ken Wharfe, condemned for writing his own Diana 'revelations' biography, dismissed the allegations in the letter as ridiculous. "It is so preposterous that it is almost laughable," he told Britain's Channel Four News.

One persistent conspiracy theory was dismissed by former coroner John Burton who said Diana was not pregnant when she died.-Reuters