Russia has confirmed that the October 31 plane crash in Sinai Peninsula, Egypt, was caused by a terrorist attack, fuelling speculation that jihadist militant group, ISIS, is responsible.

The Russian Federal Security Service director, Aleksandr Bortnikov, told President Vladimir Putin that investigation revealed that a homemade explosive was detonated mid-flight.

“During the flight, a homemade device with the power of 1.5 kilograms of TNT was detonated. As a result, the plane fell apart in the air, which can be explained by the huge scattering of the fuselage parts of the plane,” Bortnikov said.

Russia and Egypt had earlier dismissed ISIS’s claim that it was responsible for the deadliest crash in modern day Russia, which saw all 224 passengers on board killed. The group said the attack was retaliation for Russia’s offensive against it and promised more attacks.

Russia, however, reiterated its resolve to retaliate and an announcement of a $50million reward was made by Bortnikove for information leading to the capture of those responsible for the crash.

The United States and Britain had maintained all the while that the Sinai plane crash was the handiwork of terrorists.