Princess Diana's friend claims she would still be alive today if she had not dismissed her royal protection officers after being shown fake BBC evidence.
Diana agreed to talk to TV journalist Martin Bashir after he reportedly showed her false bank statements which led her to believe royal staff were spying on her. The BBC has pledged to investigate the claims.
Ex-Vanity Fair editor Tina Brown said the fake documents used to secure Diana's Panorama interview helped trigger events that ended in her death.
Ms Brown, who wrote The Diana Chronicles, claims the documents likely led the Princess to dismiss protection officers which could have stopped her Paris car crash in 1997.
The journalist, who dined with Diana in New York one month before her death, told the Express : "She had wilfully decided that she did not want any of the royal protection officers with her because she thought they were spying on her - probably thanks to Martin Bashir.
"She was at the mercy of a drunken off-duty driver who was working for [Mohamed Al] Fayed. If she had had that one thing, a royal protection officer, she'd still be alive today.
"He would never ever have driven in that way, in that reckless fashion, it just wouldn't have happened.
"There's just no way she'd be dead if she'd had a royal protection officer with her that night."
Matt Wiessler, a Panorama graphic designer, claimed that Bashir asked him to draft faked bank statements showing fake payments to royal employees.
Diana's brother Earl Spencer claims Bashir played on the Princess' paranoia to win her trust, revealing papers about the royals plotting against her and her staff betraying her, the Mail Online reports.
The Earl alleged this is what persuaded his sister to speak with Bashir in the world exclusive interview.
In the 1995 broadcast, Diana spoke of Prince Charles' infidelity when she famously said "there were three people in this marriage, so it was rather crowded."
The BBC recently said it had recovered a missing handwritten note from Diana that it claims to absolve Bashir of using false documents to get to interview her.
The broadcaster said it would hand over the long-lost note to a team of investigators.
It comes after previous claims from the broadcaster that a copy of the note was no longer in its possession and could not be produced for a 2007 Freedom of Information request.
Diana's document refers to bank statements which the organisation has said Bashir admitted to commissioning in a bid to interview the Princess.
But the BBC said the note shows Diana had not seen the papers before the interview and that they did not influence her decision to speak.
