CAIRO, Egypt (AP) _ Investigators are still sifting details for the cause of Princess Diana's tragic death, but already the hastily conceived Arab theory that she was slain in a British conspiracy has spawned a virtual industry in Egypt.

It's been propounded in magazines, best-selling books and even a court suit that blames Britain's royal family. Now comes the movie _ again speculating Diana was killed to stop her from marrying Egyptian boyfriend Dodi Fayed, who died with her.

Director Khairi Beshera says his film, tentatively titled ``The Last Supper,'' is about Diana's life, not conspiracy theories. But he adds he can't help explore the widely publicized notion that she was killed because she was about to convert to Islam to wed Fayed.

``When some say Diana was killed and she was a Muslim, I have to deal with this even if it is naive,'' Beshera, a well-known documentary director, said in an interview.

No hard evidence has been presented for a conspiracy, and British officials termed the idea absurd when it was first voiced just after Diana and Fayed were killed in a fiery Paris car crash on Aug. 31.

But that has not stopped many Arabs _ especially Egyptians _ from imagining a plot by a British establishment aghast that a Muslim Diana could wind up bearing a son named Mohammed who would be a half-brother to England's future king.

Five months after the deaths, Cairo bookshop shelves and newsstands are still piled high with magazines and books adorned with pictures of Diana and alluring titles about the ``fake'' car crash and supposed details of the couple's deaths.

A blurb on the back cover of the book ``Assassination of a Princess'' by Ahmed Atta states flatly that Diana joined a long list of world celebrities killed for political reasons.

In a chapter titled ``Who Killed Diana and Dodi,'' Egyptian journalist Atta quotes unidentified sources as saying the British intelligence agency MI6 did it.

To support his theory, Atta cites news reports that British agents spied on the princess in Paris and suggests this was part of a murder plot.

Another journalist, Ilham Sharshar of the Al-Ahram daily, says Diana confided to her friend Jemima Goldsmith, who converted to Islam to wed Pakistani cricket legend Imran Khan, that she, too, was considering becoming Muslim. It's in Sharshar's book ``Diana, a Princess Killed by Love.''

A Cairo lawyer, Nabih el-Wahsh, has put these ideas into a lawsuit seeking to blame MI6 agents for Diana's death and accusing Queen Elizabeth II of ordering the killing.

In January, a Cairo court is expected to decide if it will hear the case _ an unlikely outcome but not impossible since Egyptian courts often take up cases of perceived insults to Islam.

El-Wahsh claim he has evidence for his suit but concedes it is mostly based on Arab media reports.

For example, he plans to show the court an Arabic newspaper clip saying that when Diana visited Pakistan last year, she asked the imam of a Lahore mosque about conversion to Islam. El-Wahsh said he also will present reports that Diana already was pregnant.

``They have to kill her to prevent her from giving birth to a baby from a Muslim man,'' he said. ``It is evident like the sun ... it does not need any effort to prove it.''

Beshera, the film director, said he did not want to make a film blaming anyone for the fatal crash but a drama about Diana's life, ending with her romance with Fayed and their shocking deaths.

``It is her endless effort for emancipation and defiance of the conservative royal traditions that made me think of making a film about Diana,'' he said.

Shooting for the movie, financed by a Saudi millionaire at a cost of 2 million pounds (dlrs 588,000), will start soon, says Beshera, whose films have been shown at festivals in London, Leipzig and Rotterdam.

Known for his meticulous work, Beshera says he has collected books, news clippings and video tapes about Diana dating to her marriage to Prince Charles in 1981. He's also seeking to get close to his subject in other ways.

For example, he spent dlrs 78 for a quarter-once of a perfume Diana used _ Diorissimo, a scent of lily and jasmine. On many days, his breakfast is the muesli with yogurt also favored by Diana.

But for all his concern about Diana's life, Beshera concedes that he will have to deal with the conspiracy theory of her death in a film made with Egyptian actors for an Arab audience.

Arabs have a habit of seeing conspiracies behind almost every act. And el-Wahsh says Britain and France will have a hard time convincing the Arab public Diana's death really was an accident.

``Why do they want us to believe in the coincidence theory when they refuse to accept the conspiracy theory?'' he said.