FRENCH DETAIN 7 PHOTOGRAPHERS : THE DAY'S EVENTS.

Byline: Craig Whitney The New York Times

French police opened a criminal investigation Sunday to determine whether a chase by seven photographers on motorcycles was responsible for the car crash in Paris that killed Diana, Princess of Wales, and her companion, Harrod's heir Dodi Fayed, shortly after midnight.

Sunday evening, Prince Charles, the heir to the British throne and Diana's husband until their marriage ended in divorce a year ago, flew to Paris from Scotland and sadly accepted her body, in a plain wooden coffin, from President Jacques Chirac at Pitie-Salpetriere university hospital, near the Sorbonne.

With Diana's two sisters, Lady Jane Fellowes and Lady Sarah McCorquodale, Charles then flew back to a shocked and grieving Britain with the body.

Police did not identify the photographers except by their nationalities, six French and one Macedonian, all said to be commercial free-lance photographers working on commission for photographic agencies.

After questioning them all night, the authorities placed all seven in formal detention, which allows them to be held for 48 hours without charges. Police were said to have seized several rolls of their film.

``The inquiry will establish in more detail the role that these people may have played in the cause of the accident and how they behaved at the site,'' a statement by the Paris prosecutor's office said.

Legal experts said that detectives would look into whether the motorcycle pursuit had contributed to the accident, and whether the pursuers had violated French laws requiring immediate witnesses of an accident to try to give aid on the scene.

Some reports said that the first photographers on the scene had snapped pictures instead.

Fayed, 41, who had been linked romantically with Diana for several months, died instantly at 12:35 a.m., police said, when the powerful black Mercedes 600 sedan in which they were riding from dinner at the Ritz Hotel to an apartment in the fashionable 16th arrondissement smashed into the wall of a tunnel by the Seine and was reduced to a compressed mass of twisted glass and metal.

The driver, an employee of the hotel, which is owned by Fayed's father, Mohammed Al Fayed, the Egyptian-born owner of Harrod's, was also killed. A bodyguard, identified by French hospital officials as Trevor Rees-Jones, was injured but not in critical condition.

Fayed's body was identified at the main Paris morgue Sunday morning and buried later in the day in a swift and simple Islamic ceremony in London.

Diana, who suffered a crushed chest and head injuries, died of cardiac arrest at the hospital, where ambulance workers brought her after prying her loose from the wreckage.

Surgeons found massive internal bleeding from her heart arteries, but were unable to restore circulation and pronounced her dead at about 4 a.m. Paris time (7 p.m. Saturday, Pacific time).

The crash occurred where a riverside expressway takes a slight jog to the left and passes under the Place de l'Alma, not far from the Eiffel Tower on the other side of the Seine.

Diana and Fayed arrived in Paris on Saturday afternoon from the Italian Mediterranean island of Sardinia, where they had sailed aboard Fayed's yacht from the French Riviera, setting down in a private plane at Le Bourget airport north of Paris.

The free-lance photographers, alerted by radio, waited for them to arrive at the Ritz, the luxury hotel on the Place Vendome on the Right Bank, and followed Diana on an errand to the Champs-Elysees at about 8:30 Sunday night, witnesses said.

The couple dined at the Ritz until about midnight, according to witnesses who told French radio that a Land Rover with tinted windows took off from the Hotel then and headed toward the Place de la Concorde and the 16th arrondissement, where the Fayed family has a long-term lease on the villa that belonged to the Duke and Duchess of Windsor. They may have been trying to throw photographers from the scent of their real quarry.

Fayed and Diana, who police officials said were not wearing seat belts, got into the back seat of the Ritz Mercedes a few minutes later and raced off in the same direction as the earlier car. Seven photographers mounted motorcycles or motor scooters and took off in pursuit.

Photographers on motor scooters or motorcycles following prominent personalities around are not unusual in France.

Police and others speculate that the Mercedes driver may have tried to outrun the pursuing photographers.

All that police would say Sunday was that at about half past midnight Sunday morning, the Mercedes, racing at high speed down the westbound lanes of the main traffic artery on the Right Bank of the Seine, struck one of the square concrete pillars in the tunnel's central dividing lane.

It then hurtled full force into the right concrete wall, directly underneath the Place de l'Alma at the eastern edge of the 16th arrondissement. The speed limit in all of Paris is 30 mph, and at this point it is not known why the driver was going so fast or why he lost control.