Egypt's chief investigator says a preliminary investigation into the October crash of a Russian passenger plane in Sinai has found no indication yet of any "illegal or terrorist act."

A statement released Monday by the chief investigator, Ayman el-Muqadam, says that so far the investigation committee did not "receive any evidence" that indicates there was foul play in the downing of the plane.

The vaguely worded statement implied this is not the final conclusion of the investigators. El-Muqadam's statement also says the committee is "continuing its work."

The Oct. 31 crash killed all 224 people onboard. Russia has said an explosive device had been placed onboard the Airbus 321-200 and the Sinai branch of the Islamic State group has claimed responsibility.