Mohamed al Fayed tonight branded the decision not to appoint a jury for the Diana, Princess of Wales inquest "shocking but predictable".
Britain's top female judge Baroness Butler-Sloss is to sit alone on the high profile case.
Lawyers for Harrods boss Mr al Fayed, whose son Dodi was killed in the 1997 Paris car crash, argued in favour of a jury of ordinary men and women during legal discussions at the High Court last week.
But Lady Butler-Sloss said in her ruling today that only a coroner could give the "careful and fully reasoned decision" Diana and Dodi's inquests needed.
Mr al Fayed said he had instructed his lawyers to take all possible steps on the matter. They are currently reviewing her 34-page decision.
"For the past ten years I have fought to expose the truth about these murders; I do not intend to give up now," Mr Al Fayed said.
"The public, and in particular, a jury of ordinary people must hear all the evidence, in front of an independent and fair minded coroner.
"I have instructed my lawyers to take all possible steps towards achieving this.
"If that means that the deputy coroner for the Royal household can no longer hear the two inquests, so be it."
Lady Butler-Sloss, who wants the full inquests to start in May, has appealed for any attempts to challenge her decision to be made promptly.
The inquests are to be held jointly at a single hearing, most likely at the Royal Courts of Justice.
In order to do this, Lady Butler-Sloss is to transfer Dodi's inquest, which falls under the jurisdiction of the Surrey coroner, to the jurisdiction of the Queen's household, which Diana's inquests falls under.
Lady Butler-Sloss was appointed deputy coroner of the Queen's household and assistant deputy coroner for Surrey for the inquests, which were opened in separate locations in 2004.
A 3D model of the Pont de l'Alma tunnel crash site, created for the Metropolitan Police investigation, will be shown at the next preliminary hearing in March.
The scope of the inquests and the witnesses will also be decided then.
Lady Butler-Sloss said it would be an "opportunity for us all to see the virtual reality scene on computer created by Operation Paget".
Groundbreaking technology with data from 186 million points was used to put together the 3D model of the scene in the Pont de l'Alma tunnel to an accuracy of within one centimetre.
Lord Stevens, who was in charge of the investigation, said his team had carried out the largest and most comprehensive survey and reconstruction of the scene of an incident yet.
Mr al Fayed said the ruling was part of the "cover-up" and described the decision to treat Dodi's inquest as if had been a member of the Royal Household as "bizarre".
"Lady Butler-Sloss's most recent decision clearly continues the Establishment policy of cover-up," he said.
"It is extraordinary and bizarre that, in order to achieve this, the deputy coroner will deal with my son's inquest as if he had been a member of the Royal Household.
"Even Princess Diana had been thrown out of the Royal Household before her death.
"Now they treat them both as if they were part of the Royal Household, just to stop the truth emerging."
He added: "I am sure her next step will be to prevent most of the relevant evidence even being heard at the inquests."
Asked if Mr al Fayed wanted Lady Butler-Sloss to be replaced, a spokesman for the Harrods tycoon said: "What he wants is a coroner who also sits with a jury to hear all the evidence."
Lady Butler-Sloss previously ruled out using a jury made up of senior members of the Royal Household.
She declared last week after hearing legal argument in the High Court that such a jury, used for royal inquests, would be "inappropriate".
The inquests can proceed following the publication of Lord Stevens's findings last month, which dismissed the many conspiracy theories surrounding the fatal incidents which took place in the Pont de l'Alma tunnel in Paris on August 31 1997.
It concluded that the crash was nothing more than a tragic accident and driver Henri Paul was drunk and driving too fast.
Lady Butler-Sloss conceded last week that there were elements of the police investigation which could be questioned in court.
"There is much in what Lord Stevens's report says which is capable of challenge," she said.
Mr al Fayed maintains the couple were murdered and claims their deaths were part of a secret plot by the British establishment.
At least 40 witnesses will give evidence at the full inquest, many of them French and some appearing by video-link from Paris.
Coroners aim to confirm the identity of the deceased and the details of how, when and where they were killed.
According to British law, inquests must be held into deaths abroad if they are deemed not to have occurred due to natural causes.