LONDON (Reuters) - British hearings into the deaths of Princess Diana and her companion Dodi al Fayed will be held in public after a decision that they should be conducted in secret was reversed, judicial authorities said on Thursday.

The original decision of presiding judge Dame Elizabeth Butler-Sloss had been strongly criticized by Fayed's father Mohamed, owner of the exclusive London store Harrods.

The preliminary hearings, scheduled for next month, are the latest step in efforts to get to the bottom of the death of Diana, ex-wife of British heir to the throne Britain's Prince Charles.

Diana, who was 36, Fayed and their chauffeur Henri Paul died when their Mercedes limousine smashed into a wall in a Paris road tunnel in 1997.

A two-year French inquiry blamed the crash on Paul, saying he was drunk, under the influence of anti-depressants and driving too fast.

The British inquest was opened in January 2004 and then royal coroner Michael Burgess asked police to hold a top-level investigation into the circumstances surrounding the deaths.

He said he wanted John Stevens, the former head of London police, to examine conspiracy theories that the couple were murdered by British spies to cover royal embarrassment about their relationship.

Diana and Charles had two sons, Princes William and Harry, but their marriage ended in divorce.

Stevens is due to unveil the results of his three-year investigation next week.

The Judicial Communications Office said Butler-Sloss originally decided to hold the hearings on January 8 and 9 in private for practical reasons such as the size of a courtroom available.

"She's reconsidered in view of the strong public interest in these particular hearings that they should be held in public," a spokesman said. The proceedings would consider whether a jury should be present for a full inquest and if so, what form it would take.

A spokesman for Mohamed al Fayed, who remains convinced that the couple were murdered by British spies to prevent his son, a Muslim, from marrying Diana, welcomed the decision.

"He doesn't believe that anything should be held behind closed doors. There's no reason for it, nobody has anything to fear from the cold light of day than those who may be guilty," the spokesman told Sky News.

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