International news media are reporting that black boxes from the Russian plane that crashed in Egypt last weekend indicate the plane came to a sudden, violent end in a midair explosion.
The November 6 news reports, if confirmed, provide the first hard evidence that the plane was destroyed by a bomb, something that has been cited only as a possibility thus far by authorities from Russia to the United States.
France 2 TV is reporting that "the sound of an explosion can be distinctly heard during the flight," according to "an investigator who had access to the black box" of the Metrojet Airbus A321-200 plane.
France's accident investigation agency told AP it could not confirm the report. The agency has experts now in Egypt investigating the crash because the Metrojet was made in France.
A souce AFP described as close to the case also said the plane suffered "a violent, sudden" end, killing all 224 people on board.
The flight data recorder showed that "everything was normal during the flight, absolutely normal, and suddenly there was nothing," the AFP source said.
A separate AFP source said both the flight data and voice recorders showed "everything was normal" until both failed at 24 minutes after takeoff from the Sharm el-Sheikh resort October 31, pointing to "a very sudden explosive decompression."
The data "strongly favors" the theory that someone planted a bomb on board the plane, the second AFP source said.
An Egyptian affliate of the Islamic State group has claimed it downed the plane in retaliation for Russian air strikes in Syria.
A video released by IS November 6 purports to show the extremist group's leaders in Aleppo congratulating their counterparts in Sinai after the crash, CNN reported.
Separate reports out of the United States and Britain November 6 said intelligence agencies intercepted "chatter" after the crash between IS leaders in Raqqa, Syria, and militants in the Sinai Peninsula boasting about downing the plane.
"They were clearly celebrating," NBC Nightly News quoted a U.S. official as saying.
U.S. intelligence also intercepted a message from IS's Sinai Province affliate before the crash that warned of "something big in the area."
The shattered bodies and debris from the plane, which broke up at 31,000 feet, fell into the northern Sinai region where the militant group is based.
"What Daesh is saying has a good chance of being credible," a European official briefed by intelligence sources told Reuters. "The theory of an explosive device, with local complicity, is being taken seriously."
The reports have been credible enough that most major countries -- including Russia -- have either suspended flights to Egypt's Red Sea resorts or beefed up security there or instituted both measures.
Russia had played down the possibility of a bomb for days before announcing November 6 that it is suspending all passenger flights to Egypt.
A Russian investigator told TASS that the Russian side so far has no evidence confirming an onboard bomb explosion, but it is requesting that French investigators share their evidence.
"As of now, we can speak only about certain noises recorded by the cockpit voice recorder," the investigator told TASS.
"It is too early to say that the nature of these noises is identified, moreover, to say that they indicate an explosion," the source said. "We have no such data. We will ask the French and the Egyptians to provide concrete proof of their theories."
Meanwhile, the head of Russia's emergencies ministry said Russian experts had taken samples from the crashed jet and were testing them for any traces of explosives.
With reporting by AFP, France 2 TV, AP, Reuters, CNN, and TASS