"The logical explanation is that an explosion brought it down," the official told The Associated Press.
The official, who is part of the Egyptian team investigating the crash that killed all 66 people on board the flight from Paris to Cairo early last Thursday, has personally examined the remains at a Cairo morgue.
He spoke on condition of anonymity because he was not authorised to release the information.
"But I cannot say what caused the blast," he said. Egyptian authorities have said they believe terrorism is a more likely explanation than equipment failure, and some aviation experts have said the erratic flight reported by the Greek defense minister suggests a bomb blast or a struggle in the cockpit. But so far no hard evidence has emerged.
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An independent Cairo daily, al-Watan, quoted an unnamed forensics official in its edition today as saying the plane blew up in midair but that it has yet to be determined whether the blast was caused by the an explosive device or something else.
In a search for clues, family members of the victims arrived Tuesday at the Cairo morgue forensics' department to give DNA samples to help identify the remains of their kin, a security official said.
The official also spoke on condition of anonymity because he was not authorized to talk to reporters.
Egypt has dispatched a submarine to search for the flight's black boxes and a French ship joined the international effort to locate the wreckage and search for the plane's data recorders.