A bomb most likely caused the crash of a French DC-10 jetliner that exploded in the sky Tuesday over a desolate stretch of northern Africa with 171 people on board, the airline said Wednesday.

The French airline UTA also said it received an anonymous call from a man claiming responsibility for the crash on behalf of the Moslem terrorist group Islamic Jihad. The airline said it was not in a position to judge its authenticity and informed the French Foreign Ministry.The wreckage of the aircraft was found scattered widely across the rocky, sandy and remote section of south-central Niger. Rescue crews were en route to the region, but the terrain was reported to be too treacherous for aircraft to land.

There was no word on survivors. The wife of the U.S. ambassador to Chad and a Chadian Cabinet minister were among those reportedly aboard.

Contact was lost with the Paris-bound jet less than an hour after it took off Tuesday from the capital of Chad, N'Djamena, after originating in the Congo.

"It exploded at high altitude, leaving every reason to believe it was a bomb," UTA airline spokesman Michel Friess said on French television. He said it was possible, but less likely, that a technical failure was to blame.

There was no way the claim of responsibility could be verified. Islamic Jihad is among several radical fundamentalist groups in Lebanon presumed to be part of Hezbollah, the Iran-financed guerrilla group that is believed to hold most of the 16 Western hostages in Lebanon, including eight Americans.

On March 10, 1984, a bomb exploded on a UTA DC-8 on the same route just before the plane was to take off from N'Djamena, injuring 25 people on board. An otherwise unknown group calling itself "Group Idriss Miskini" claimed responsibility, but the Chadian government blamed Libya for the bombing.

Chad fought with Libyan-backed rebels for more than a decade, but the situation has been calm for the past two years, and Chad and Libya recently signed an agreement to settle their border dispute peacefully.

Among the passengers who boarded in N'Djamena was Bonnie Pugh, wife of the U.S. ambassador to Chad, Robert L. Pugh, the U.S. Embassy in Chad said.

The French news agency Agence France-Presse, quoting unidentified sources, said Chadian Planning Minister Mahamat Soumahila was also on the plane, headed for the annual meeting of the International Monetary Fund in Washington.

Most passengers appeared to be French, Chadian and Congolese, said the Foreign Ministry spokesman. He said that a more thorough breakdown, if issued at all, would have to await notification of the next of kin.

There were 156 passengers and 15-member crew on board, the airline said. A UTA spokeswoman declined to say when or if a complete passenger list would be made public.

The wreckage was found shortly after dawn by a Transall aircraft sent by the French military contingent in N'Djamena. The Defense Ministry said the wreckage was spread over a wide rocky and sandy area in the Termit mountains, north of Lake Chad.

French military spokesmen said twin-engine Puma helicopters were being dispatched from N'Djamena with medical crews for immediate aid to survivors, if any are found. The Transport Ministry said it was sending investigators.

Even before the rescue helicopters arrived at the scene, President Francois Mitterrand expressed "his personal condolences to the families of the victims," during a Cabinet meeting, government spokesman Louis Le Pensec said.

UTA said the last radio contact between the plane and air traffic controllers indicated everything was normal. It reported no unusual weather.

The airline purchased the aircraft in 1973 and it had logged 60,000 hours in the air. UTA said the plane was in excellent condition.