By Stephen M. Silverman
October 20, 2003 07:30 AM

Princess Diana believed there was a plot afoot to kill her in a car crash, according to a secret letter made public Monday by her former butler, Paul Burrell.

The late former wife of Prince Charles apparently wrote about her fears in October 1996, just 10 months before she died in a Paris road tunnel, according to an excerpt from Burrell’s book “A Royal Duty,” which appears in the Mirror newspaper.

Diana gave Burrell the letter for safekeeping, the book says. For legal reasons, the Mirror deleted the identity of the person Diana named.

“This particular phase in my life is the most dangerous,” the excerpt quotes the letter as saying. “(Deleted word(s)) is planning ‘an accident’ in my car, brake failure and serious head injury in order to make the path clear for Charles to marry.”

Burrell’s book claims that before sealing the letter in an envelope marked “Paul,” Diana told her trusted butler: “I am going to date this and I want you to keep it … just in case.”

A spokesman for Buckingham Palace declined comment on the letter, according to Reuters.

Piers Morgan, editor of the Mirror, told BBC radio that he has no reason to doubt the authenticity of the letter. “Paul Burrell is about as reputable as it comes … when it comes to the testimony and legacy of Princess Diana,” he said.

Robert Lacey, a royal biographer, said the letter was an “extraordinary revelation and prophecy” which was bound to add to the raft of conspiracy theories on how and why Diana died. Lacey also reportedly verified that the handwriting looks exactly like Diana’s.

“There is something magic about this,” Lacey told Reuters. “People will say forever now that Diana foretold her death. And that will add to the magical aura — the supernatural and the prophetic — that surrounds Diana.”

In its next issue, PEOPLE publishes an exclusive excerpt from Burrell’s book.