Russia vows revenge after confirming bomb attack brought down passenger jet over Egypt

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

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 (47 million-euro) reward for information leading to capture of those responsible.

"It is not the first time that Russia confronts barbarous terrorist crimes", Russian President Vladimir 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 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 Islamic State group killed at least 129 people in Paris.

Russia's security chief Alexander Bortnikov told 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 Bortnikov said.

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

- 'Intensify'

A group linked to IS 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.

Putin did not expressly blame IS for the attack on the passenger jet but pledged to step up air strikes in Syria where Moscow is conducting a bombing campaign it says is targeting the IS 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," Putin said.

A US defence official said that Russia on Tuesday staged a "significant number" of air strikes on the Islamic State 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 US official said it had given Washington advanced warning of the attacks.

France has ratcheted up its strikes against IS targets around Raqa since the bloody attacks in Paris and President Francois Hollande said he will try to meet US President Obama and Putin in the coming days to discuss the fight against the jihadist group.

The security meeting and the announcement on the bomb attack came shortly after Putin returned from discussing the Syria conflict with world leaders including President Barack Obama at the G20 summit in Turkey.

Russia has been conducting strikes in Syria since late September in support of the forces of President Bashar al-Assad while the US and its allies are flying a separate campaign targeting IS.

Putin has called for a united coalition against IS in Syria and on Monday reiterated that the attacks in France showed that it was "indispensible" to join forces against the jihadists.

Russia and other key international players are currently engaged in the broadest diplomatic push yet to end the war in Syria but Moscow disagrees with the West over the fate of Assad.