France wants to assist Egyptian authorities investigating the crash of a charter plane off the coast of Egypt on Saturday that killed 148 people, most of them French tourists.

Egyptian officials and the charter's owner, Flash Airlines, say they believe the crash was due to a technical failure. But the French Justice Ministry has requested that prosecutors open a preliminary inquiry for involuntary homicide, or manslaughter.

The ministry said the request by French Justice Minister Dominique Perben would not prejudice the inquiry, but rather would give investigators a procedural framework to work with.

Legal experts say the request allows France to send investigators to the scene to work alongside Egyptian officials in determining the exact cause of the crash.

Meanwhile, French officials have set up a crisis unit for relatives and friends of the victims. And a number of top-level French officials, including Prime Minister Jean-Pierre Raffarin, were on hand at Charles de Gaulle airport near Paris, where the Boeing 737 had been scheduled to arrive Saturday morning.

Most of those killed were French tourists believed to be on their way home after Christmas vacation.

French President Jacques Chirac telephoned his Egyptian counterpart, Hosni Mubarak, for a briefing on the circumstances of the crash. The French leader also dispatched a high-level foreign affairs official, Renaud Muselier, to Egypt.

French Transportation Minister Dominique Bussereau told reporters the aircraft appeared to be having problems as it tried to turn around shortly after taking off from the Egyptian tourist resort of Sharm el-Sheikh.

Fears of terrorist attacks targeting airlines have been heightened over the holiday season. Six Air France flights from Paris to Los Angeles were canceled last week because of security concerns.

British Airways has also canceled or delayed a number of flights because of concerns over possible terrorist threats.