A bomb that downed a Russian plane in Egypt last month had been placed in the aircraft's main cabin not in the cargo compartment as reported earlier, the daily Kommersant said on Wednesday citing an unnamed source.

The newspaper, citing a source close to the investigation of the crash, said the epicentre of the explosion appeared to have been at the rear of the cabin near the tail section.

"According to a preliminary version, the bomb could have been laid under the passenger seat by the window. Its operation has led to the destruction of the frame and depressurisation of the cabin, which had an explosive character," the newspaper said.

All 224 people on board were killed. President Vladimir Putin vowed on Tuesday to hunt down those responsible and intensified air strikes against militants in Syria. – Reuters