The Russian aircraft disintegrated in midair before it crashed over Egypt's Sinai Peninsula on Saturday, state-run Ahram newspaper reported on Sunday.
Ahram said an official with Russia's Interstate Aviation Committee said in an interview with Russian RIA-Novosti news agency that the disintegration happened in the air and the fragments are strewn over a large area.
Russian Chief of invitation panel Viktor Sorochenko said it was too early to determine the cause of the tragic accident.
Sorochenko leads an international committee made up of experts from Russia, Egypt, France and Ireland to probe into the incident. The investigation has begun early on Sunday, starting with analyzing the plane's two black box data recorders, which have been recovered late Saturday.
Meanwhile, the Egyptian Forensic Medicine Authority (FMA) started to deliver the bodies of the victims of the Russian plane to the Russian Embassy in Cairo and victims' relatives.
As many as 187 dead bodies were found so far in the scene of the crash, official MENA news agency reported.
Initial investigation showed that there were no eye-witnesses despite some videos of the accident posted online that were found fake.
The Egyptian cabinet said on Sunday that the search has widened after finding bodies scattered across eight square km.
A Russian airliner, with 224 passengers and crew, crashed into a mountainous area in the restive Sinai on Saturday.
A militant group affiliated to Islamic State in Egypt claimed responsibility for the crash, but the claim could not be verified.
Egyptian Prime Minister Sherif Ismail said on Saturday it was impossible to determine the cause of the Russian plane crash until the black box was examined.
"Experts asserted that a plane flying that high technically cannot be shot down," Ismail said, adding that no "irregular" activities were believed to be behind it.
