Mohamed al Fayed claims the former prime minister sanctioned the "momentous and horrific action" that saw his son Dodi Fayed and Diana, Princess of Wales killed in a car crash in Paris, their inquests were told.

The Harrods boss - described to the hearing as both a buccaneering businessman and a grieving father - entered the witness box and implicated many establishment figures in the plot to kill or cover-up the murder of the couple.

Everyone from the security services, including MI6 and the CIA, the French authorities, former Metropolitan Police chiefs Lord Condon and Lord Stevens and even Diana's own sister Lady Sarah McCorquodale came under Mr al Fayed's veil of suspicion.

The Duke of Edinburgh was placed at the centre of the allegations as Mr al Fayed believes he ordered MI6 to orchestrate the crash that killed Dodi, Diana and their driver, Henri Paul, on August 31 1997.

Asked by the coroner's counsel Ian Burnett QC if he still stood by the claim made in his statement that "I'm in no doubt whatsoever that my son and Princess Diana were murdered by the British security services on the orders of Prince Philip, Duke of Edinburgh", Mr al Fayed replied: "Yes."

Many powerful and high profile figures were verbally attacked from the witness box by the Egyptian businessman. Describing Diana's life with senior royals, he said: "She suffered for 20 years, this Dracula family."

While the Prince of Wales's wife the Duchess of Cornwall was compared to a reptile.

Commenting on his belief that Charles was part of the conspiracy to kill Diana, he said: "They finished her, they murdered her and now he is happy. He married his crocodile wife and he is happy with that."

The most scathing comments were reserved for Prince Philip who was labelled a "Nazi" and "racist" by the tycoon. He told the hearing: "Here is an article. I would like to show it to you, walking with a Hitler General when he was 15 years old. Here it is. You want someone like that, growing up with the Nazis, accept(ing) my son? "There is no way. This is the proof again."