Princess Diana and Dodi Al Fayed were murdered, Dodi's father Mohamed Al Fayed has told the inquest into their deaths in a car crash in Paris in 1997.
Harrods owner Mr Al Fayed claimed former prime minister Tony Blair, MI5, MI6 and the British ambassador to France were all part of the conspiracy.
And he said Princess Diana "knew Prince Philip and Prince Charles were trying to get rid of her".
He also said Diana had told him she was pregnant, and the couple were engaged.
"I am the only person they told," he said.
Asked by Ian Burnett QC, counsel to the inquest, if he stood by his claim that Diana and Dodi were "murdered by the British security services on the orders of Prince Philip, Duke of Edinburgh", Mr Al Fayed replied: "Yes."
He also pinpointed alleged security forces in the ambulance crew, the then British Ambassador to France Sir Michael Jay and the princess's brother-in-law Sir Robert Fellowes as all being involved in the plot.
And he said Prince Charles was complicit, hoping to make way so he could marry his "crocodile wife" Camilla Parker Bowles.
The Harrods boss also raised concerns about a note written by Diana's divorce lawyer, Lord Mishcon, after an October 1995 meeting. It outlined her fears there was a plot to kill her in a car crash.
The police agreed to hand it to the coroner only after Diana's former butler, Paul Burrell, produced a note from the princess making similar allegations in the Daily Mirror in October 2003. By that time, Sir John Stevens led the Met.
Mr Al Fayed said this delay confirmed his "belief that my son and Princess Diana were murdered".
In his evidence, Mr Al Fayed branded Prince Philip a "Nazi" and a "racist" and said: "It's time to send him back to Germany from where he comes."
"You want to know his original name - it ends with Frankenstein," he added.
Mr Al Fayed read out a statement detailing his main concerns about the crash, and the points he felt the inquest should address.
Diana had told him she kept a wooden box and if anything happened to her, the contents should be made public, he said. But it had not been kept safe by Diana's butler Paul Burrell, or her sister, Lady Sarah McCorquodale.
He also said blood samples apparently taken from driver Henri Paul - who was also killed in the crash - did not belong to the Frenchman.
Mr Al Fayed felt the murder was likely to have been carried out by photographer James Andanson, who has since died, on the orders of the security services.
He also said bodyguard Trevor Rees - the only survivor of the Paris crash - was "turned against" him by MI6, as were his colleagues Kes Wingfield and Ben Murrell.
During his evidence, Mr Al Fayed held up a copy of Monday's Sun newspaper, which claims Paul Burrell said he had not told the whole truth to the inquest.
He said of Mr Burrell: "He's been sitting here in the witness box talking about baloney things. It's important to bring him back."
'Dignity in death'
Lord Justice Scott Baker later told the court: "This is something that's certainly being investigated."
The coroner said he had called for the Sun's tape and would want to know the circumstances under which it was obtained.
Richard Horwell QC for the Metropolitan Police Commissioner put it to Mr Al Fayed that he had denied Diana "dignity in death" by raising the question of her pregnancy.
The barrister added that "witness after witness" had been asked about her method of contraception and her menstrual cycle, "and the evidence shows she could not have been pregnant".
Mr Al Fayed replied: "All the witnesses who have been saying this are part of the cover-up and have been told what to say."
The Harrods owner broke down when asked about the moment he was told Dodi was dead.
He said someone from security told him, but when asked if he remembered a call from Ritz hotel president Frank Klein, he answered: "It's difficult. I'd like to know why you are asking me things like that."
Mr Klein has told the inquest he telephoned Mr Al Fayed to break the news and he replied: "This is not an accident."