BUCHAREST -- A forensic expert examining the remains of the 60 people killed in Romania's worst-ever air crash said Monday he believed that an in-flight explosion was responsible for the disaster.


A formal commission investigating Friday's crash declined to theorize on its causes. But Dr. Vladimir Belis, head of Bucharest's Forensic Institute, which is working to identify the victims, said he was certain of an in-air explosion.


Seven forensic experts from Belgium and two from the United States were assisting with the identification.


"My personal opinion ... is that the deaths occurred within seconds while the plane was still in the air,'' Belis said. "The body parts were partially burned, and the way they looked was very specific to an explosion.''


Another expert agreed. "It was an explosion,'' Ovidiu Traichoiu, director of the Otopeni airport and air traffic control, said. "But we don't know whether it was a bomb or a technical defect.''


Even as investigators analyzed the flight data recorders Monday to help them determine why the Tarom airlines Airbus A-310 nose-dived shortly after take-off for Brussels, a bomb scare resulted in new jitters at the carrier.


Bucharest's Otopeni airport was closed for about four hours Monday morning . An anonymous caller said a bomb was aboard an already-airborne plane bound for Paris, national radio cited airport chief Constantin Tudose as saying. The plane made an emergency landing in Timisoara, in western Romania, and was being searched.


Also the French Embassy in the Romanian capital said it had received an anonymous phone call from a man claiming responsibility for Friday's crash.


Joseph Casals, press attache at the French Embassy, said the man called the embassy Saturday afternoon, a day after the air disaster. The man, who spoke in French, made no claims for any group or individual and did not give his name, Casals said.


The embassy informed the Romanian government.