Sinai plane downed by terrorist bomb, says Russia

Russia's spy chief has said that a homemade explosive device destroyed a Russian passenger plane that crashed in Egypt's Sinai region.

Alexander Bortnikov, the head of the FSB intelligence agency, told President Vladimir Putin that the crash was an act of terrorism.

"One can say unambiguously that it was a terror act," Bortnikov said, adding that the plane disintegrated in midair due to a bomb with the equivalent of a kilo of TNT.

In remarks released by the Kremlin on Tuesday, Putin vowed to find and punish the attackers and said he would step up air strikes against "criminals" in Syria.

"We will search for them anywhere they might hide. We will find them in any part of the world and punish them," Putin said.

"The combat work of our aviation in Syria must not only be continued. It must be intensified so that the criminals understand that vengeance is inevitable."

The FSB said it would pay $50m for information leading to the arrest of those who brought down the plane.

All 224 people on board plane A321, most of them Russian tourists, were killed when it crashed shortly after take-off from Sharm el-Sheikh on 31 October.

Bortkinov said: "According to an analysis by our specialists, a homemade bomb containing up to one kilo of TNT detonated during the flight, causing the plane to break up in mid air, which explains why parts of the fuselage were spread over such a large distance."

He said that traces of foreign-made explosive had been found on the personal belongings of plane passengers.

The Islamic State group has claimed it ordered the attack.