Russian President Vladimir Putin (centre), defence minister Sergei Shoigu, Russian Army Chief of Staff Valery Gerasimov, head of the Federal Security Service Alexander Bortnikov and foreign minister Sergei Lavrov observe a minute of silence ahead of a meeting on the results of the investigation into the Russian MetroJet Airbus A321 crash at the Kremlin (Photo: AFP)

Russian President Vladimir Putin vowed vengeance as Moscow on Tuesday confirmed that a bomb attack brought down a Russian passenger jet over Egypt in October, killing all 224 people on board.

Mr Putin pledged to ramp up Moscow’s bombing campaign in Syria in response to the attack but stopped short of blaming any one group as the country’s security agency announced a $50 million reward for information leading to capture of those responsible.

“It is not the first time that Russia confronts barbarous terrorist crimes”, Mr Putin said in a meeting with his security chiefs.

“The murder of our people in Sinai is among the bloodiest crimes in terms of victims,” he said in comments released on Tuesday, vowing to hunt down those responsible.

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

The confirmation of the attack — the deadliest against a Russian target since the Beslan school massacre by Islamist rebels from the North Caucasus in 2004 — comes days after a chain of attacks claimed by the ISIS group killed at least 129 people in Paris.

Egypt’s civil aviation minister, Hossam Kamal, said on Tuesday that the probe into the Russian airplane disaster has yet to reach any final conclusions, state television reported. The Cairo government later said in a statement that it was taking “into consideration” the Russian confirmation that the plane was brought down with a bomb.

Egypt also said it is enhancing security in airports after the Russian announcement.

Russia’s security chief Alexander Bortnikov told Mr Putin that the passenger jet carrying tourists back from Egyptian resort Sharm el-Sheikh on October 31 was brought down shortly after take-off over the Sinai peninsula by a home-made bomb containing explosives of “foreign production” with a force equivalent to one kilo of TNT.

“We can say unequivocally that this was a terrorist attack,” Federal Security Service (FSB) head Mr Bortnikov said.

The FSB later said it would pay “$50 million for information helping to arrest the criminals.”

A group linked to ISIS had earlier claimed responsibility for downing the plane, and Russia had halted all flights to Egypt despite refusing to endorse growing suspicions in Britain and the United States that the plane was blown up by a bomb.

Egyptian authorities have detained two employees of Sharm al-Sheikh airport for questioning in connection with the downing of the plane, two security officials and an airport employee said on Tuesday.

Mr Putin did not expressly blame ISIS for the attack on the passenger jet but pledged to step up airstrikes in Syria where Moscow is conducting a bombing campaign it says is targeting the ISIS and other “terrorist” groups.

“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,” Mr Putin said.

A US defence official said that Russia on Tuesday staged a “significant number” of airstrikes on the ISIS group stronghold of Raqa in Syria that may have involved cruise missiles fired from sea and long range bombers.

Moscow did not confirm the strikes but the United States official said it had given Washington advanced warning of the attacks.