LONDON -- The year before Princess Diana died, she was alienated from her brother, Earl Spencer, and he wrote to her saying she had mental problems and was manipulative and deceitful, a newspaper reported Wednesday.
Spencer, speaking on NBC's "Today" show, said the letter, published in excerpts from a new book, was being seen out of context and that he "adored Diana."
Worldwide television audiences watched him in September 1997 give a funeral oration about his sister, in which he spoke of their closeness as children, honored her memory and appeared to make a veiled criticism of the royal family.
He also said Wednesday that he did not believe her fatal 1997 car crash was planned, despite a letter, published in the same book, in which Diana said she feared someone would tamper with her car's brakes.
Both letters are from "A Royal Duty," a forthcoming book by Diana's former butler Paul Burrell, which is being excerpted in the Daily Mirror newspaper.
Spencer told NBC he hadn't seen the letters but had heard from handwriting experts that published sections appeared to have been written by Diana.
The princess's companion Dodi Fayed also was killed in the crash; his father, Mohammed al Fayed, has never accepted the French verdict that driver Henri Paul's use of drugs and alcohol, and the car's high speed, caused the accident. Paul also was killed. Al Fayed says the deaths were intentional.
"My family and I are absolutely certain that we've never seen any evidence of that whatsoever," Spencer said, speaking to NBC from Toronto. As for Diana's fears, he said, "I do think it's just a horrible coincidence, rather than actually tied in with reality."
Asked if Diana's fears were justified, Spencer said she had spoken to him about being eavesdropped on and having her private quarters bugged.
"I think paranoid's a very strong word but I think using it in the common way meaning very, very concerned about yourself, yes, she was at times," Spencer said.
The letter attributed to Spencer and published in the Daily Mirror said, "I know how manipulation and deceit are parts of the illness. I hope you are getting treatment for your mental problems."
Spencer told NBC the letter was being seen "out of context and out of time."
"I suppose all of the loving letters I sent won't sell like this one, which is trying to help her when she was at her most complex," he said. "Anyone who tries to make out that I didn't support and love my sister is way off the mark."
News reports have said Queen Elizabeth II and Prince Philip are furious that Burrell included private letters from Philip in the book and are considering legal action.
A palace spokeswoman declined to say whether the royal couple was upset to see the letters in print and would not comment on the possibility of a lawsuit.
She said the royal family asked to see an advance copy of the book, and the publisher responded by sending excerpts to Buckingham Palace.
Burrell, the servant whom Diana once called "my rock," said Prince Philip sent Diana a series of letters in 1992 as her marriage was foundering.
The Daily Mirror reported Tuesday that Philip wrote to Diana that he held her partly responsible for the breakdown of her marriage to Prince Charles, but also told her he "never dreamed" that Charles would leave her for longtime companion Camilla Parker Bowles.
"I cannot imagine anyone in their right mind leaving you for Camilla," Philip wrote.
But he also chastised his daughter-in-law for her own behavior, asking "Can you honestly look into your heart and say that Charles's relationship with Camilla had nothing to do with your behavior towards him in your marriage?"
A former senior royal aide defended Burrell's decision to reveal details of personal letters from her royal in-laws in the new book.
Mark Bolland, who for six years was deputy private secretary to Prince Charles, said the book simply highlighted the monarchy's inadequacies.
"Diana had many remarkable qualities. The most important for the monarchy was her ability to connect with people and to champion important causes in a highly focused and disciplined way," Bolland wrote in Wednesday's Daily Mail newspaper.
"Try as they might (and they don't often even try), there is little most of the royal family can do to build bridges successfully with those parts of the population whose support is crucial for their survival," Bolland added.