Twitter accounts connected to ISIS in the Egyptian Sinai posted a link to an audio message Wednesday in which the terror group claimed responsibility for the crash of the Russian airliner last Saturday.
The message expressed anger at those who doubt ISIS downed the Metrojet plane. It claimed there is information on the airplane's black box indicating how the aircraft crashed.
In the audio recording, which could not be authenticated by WND, a man identified as a leader of ISIS in the Egyptian Sinai says in Arabic: "We know that there are people who are still doubting that our claim of responsibility last week was false and that it was a lie. We invite you to check the black boxes of the plane and to discover whether we are right or not."
Advertisement - story continues below
The message warns so-called infidels to join Islam and to stop fighting Muslims, "otherwise you will be facing people who do not fear death."
TRENDING: Ivanka Trump made a quiet visit to Maui after the wildfires
The ISIS spokesman complained "there are people who are still doubting our responsibility."
"How dare you doubt the operation for Allah.
Advertisement - story continues below
"We say that we will not tell you know how we did crash it. Check the black boxes and you will find it out. We crashed the plane at the first year day in which we pledged allegiance to the caliph.
"We will give the detail when we will find the suitable moment to tell everybody how we crashed the plane.
Meanwhile, investigators began analyzing the information from the flight data recorder and cockpit voice recorder Wednesday, sources in Egypt's civil aviation ministry told NBC News.
The message from ISIS ended with a dire warning.
"Meanwhile we tell you, the Romans (Christians) we will be killing your soldiers, taking your money and properties and invading you in your homes and your countries we will be taking your wives as prisoners."
Advertisement - story continues below
The Russian passenger jet was en route from the Egyptian resort of Sharm el-Sheikh to St. Petersburg, Russia, when it crashed Saturday, killing all 224 people aboard.
Authorities said the wreckage covered several square miles of desert, indicating the plane disintegrated while at a high altitude.
A news agency in St. Petersburg, Fontanka, reported forensic experts who are identifying the victims said the injuries align with an explosion, "such as metal pieces in bodies," CNN reported.
No distress calls were reported from the plane, which suddenly dropped off radar about 23 minutes after takeoff, officials said.
Advertisement - story continues below
U.S. officials have reported a satellite recorded a midair heat flash just before the crash.
The London Daily Mail said doctors reported finding many of the bodies had horrific burns that apparently happened just before death.
The paper said his comments add further weight to evidence the Metrojet plane suffered an explosion or catastrophic fire that caused it to break up mid-air.
The report also noted the cockpit voice recorder revealed strange sounds shortly before the Airbus 321 disappeared from radar.
Investigators said that among the lines of inquiry were the truck that delivered fuel to the airplane before takeoff and the people who delivered food supplies to the jet.