The Duke of Edinburgh will not be called to give evidence at the inquest into the death of Princess Diana, the coroner has stated.
Mohammed Al Fayed has accused Prince Philip of a murder plot
Lord Justice Scott Baker also said the Queen should not be asked to answer questions posed by Michael Mansfield QC, representing Mohammed Al Fayed.
He said: "Neither step will in my judgement further the inquest process."
Mr Al Fayed has claimed Prince Philip and MI6 were behind a plot to murder Diana and Mr Al Fayed's son, Dodi.
Lord Justice Scott Baker ruled: "In my judgment it is not expedient to call the Duke of Edinburgh to give evidence, nor do I think the Queen should be asked to answer the questions posed by Mr Mansfield."
Mr Al Fayed was said to be "extremely disappointed" and considering the possibility of a judicial review of the ruling.
"He hopes the coroner will make publicly known his reasons for the decisions," said his spokeswoman Katharine Witty.
Earlier at the High Court hearing, Mr Al Fayed's former spokesman Michael Cole denied that he had been part of a plot to pervert the truth.
Mr Cole asked Richard Horwell QC, for the Metropolitan Police, to take back an "implication" that he had been involved in a conspiracy.
"I do not ask for apologies but I would like that to be withdrawn. I was not and I am not," he said.
He waited for a response but there was silence in the courtroom until Mr Cole said: "I hear nothing."
Mr Cole was making a second appearance in the witness box to answer allegations which had been made by later witnesses.
Ben Murrell, security manager at Harrods owner Mr Al Fayed's Paris home, has told the jury he was encouraged to embellish details of Diana and Dodi's relationship.
The couple, and their driver Henri Paul, were killed in a car crash in a Paris road tunnel in the early hours of 31 August 1997.
Meanwhile, the Metropolitan Police has said it will not launch a perjury investigation into ex-royal butler Paul Burrell until the inquest, expected to last until April, concludes.
The coroner had asked him to explain discrepancies between his evidence and reports in the Sun newspaper. Mr Burrell denies any wrongdoing.