High-level Egyptian aviation and safety experts began listening to the cockpit voice recording and analyzing flight data from EgyptAir Flight 990 yesterday, while U.S. and Egyptian officials emphasized their desire to cooperate on the probe into the fatal crash.

Egyptian Ambassador Nabil Fahmy told reporters after hearing the recording that he found it "disturbing," but declined to elaborate. He said both governments want to establish what caused the Boeing 767 to plunge into the Atlantic Ocean.

"It's a professional, cooperative effort between professionals belonging to governments who have very strong relations," Fahmy said. "Both sides want to know the truth and we're working to achieve that."

National Transportation Safety Board investigators, since synchronizing the voice and flight data recorders, have found no evidence so far that a mechanical problem or bad weather caused the aircraft to plunge from 33,000 feet into the waters 60 miles off the coast of Massachusetts. All 217 people on board were killed. Their attention was centered on co-pilot Gameel Batouti, who they think intentionally crashed the airliner and resisted his captain's pleas to help take the plane out of its death dive.

The NTSB had planned to turn the probe over to the FBI for a criminal investigation, but held off after Egypt protested.

Deputy Attorney General Eric H. Holder Jr. said yesterday that no final decision about transferring the probe to the FBI would be made without consulting the State Department and other U.S. government agencies, and considering the Egyptians' point of view. He said a determination will be made within days, adding that the Egyptian government would not have veto power over the decision.

"We need to have some further discussions with them before any decisions are ultimately made," Holder said. "But I would not say anything is contingent upon the approval of the Egyptian government."

The Egyptian group includes officials from EgyptAir, the Egyptian civil aviation authority and other agencies, according to Abdel Aleem Abyad, a spokesman for the Egyptian Embassy.

"Anybody that would have any significant bearing on this investigation is here," Abyad said.

Under normal safety board rules, few people would have access to the cockpit voice recording. Four Egyptians were given access after the initial listening by NTSB and FBI investigators, sources said. Allowing additional Egyptian officials to listen appears to be a bow to international diplomacy.

Clinton administration officials are eager to prevent the investigation from jeopardizing relations with Egypt, one of Washington's closest Arab allies, and State Department officials yesterday urged reporters to exercise caution in speculating on the cause of the crash. Egyptian officials have complained bitterly to their U.S. counterparts about what they regard as the leaking of inaccurate or incomplete information.

Ivan Eland, director of defense policy studies at the Cato Institute, a think tank, said the United States acted appropriately on Egypt's request to defer transferring the probe to the FBI.

"There are sensitivities here, and you don't want to impugn anybody's honor or integrity if that is not what really happened," Eland said. "It was probably a good idea to take it slow."

U.S. investigators emphasized that the co-pilot's Arabic statements near the end--including a phrase that translates as "I put my faith in God"--are not the sole reason the safety board wanted the FBI to take over the probe. If some mechanical problem or an alarm had appeared on either of the recorders, the co-pilot's words likely would have been considered insignificant.

Instead, they said, the decision was based in part on a circumstantial chain of events revealed by the preliminary analyses of cockpit voice recorder and flight data, including:

* The flight data recorder and cockpit voice recorder contain no evidence of any mechanical problem or any abnormal sound that might raise suspicions of a mechanical or electrical problem.

* There is no evidence of a fire, cabin depressurization or any alarm before the plane was well into the dive.

* The co-pilot--whom they believe was Batouti--was alone in the cockpit. He manually clicked off the autopilot, but did not act as if he had an emergency. For eight seconds, he calmly steadied the plane by hand.

* The dive was induced by the co-pilot by lowering power on the engines and pushing down on the elevators--devices on the tail that control a plane's altitude--which pushed the 767's nose down into an increasingly steep dive.

* The captain returned to the cockpit and the elevators moved in different directions, something that can happen only if strong pressure is placed on the plane's control columns. The co-pilot's controls were pushed in a direction that would take the plane down.

Staff writer John Lancaster contributed to this report.