Russia confirms bomb attack brought down Egypt plane, vows revenge

"It is not the first time that Russia confronts barbarous terrorist crimes", Russian President Vladimir Putin said in a meeting late Monday with his security chiefs.

"The murder of our people in Sinai is among the bloodiest crimes in terms of victims. We will not wipe away the tears from our soul and hearts. This will stay with us forever but will not stop us finding and punishing the criminals," he said in comments released Tuesday.

"We will search for them anywhere they might hide. We will find them in any part of the world and punish them," he said, calling the attack "one of the bloodiest crimes".

Russia's security chief Alexander Bortnikov told Putin that the passenger jet was brought down over the Sinai peninsula by a bomb 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.

In response to the attack Putin pledged to step up air strikes in Syria where Moscow is conducting a bombing campaign it says is targeting the Islamic State group 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 group linked to IS had earlier claimed responsibility for downing the plane but Russia had said it was waiting for the official results of an investigation into the tragedy.