People mourn at memorial for Metrojet Flight 9268
People mourn at memorial for Metrojet Flight 9268Reuters

As the investigation into the downing of a Russian passenger jet over Egypt's Sinai Peninsula leans increasingly towards terrorism as the cause, the Islamic State (ISIS) jihadist group which has already claimed responsibility has released a video celebrating the attack.

The video, posted online by ISIS's media arm on Tuesday, and translated by the Middle East Media Research Institute (MEMRI), shows jihadists handing out candy to children and men in ISIS-held territory in either Iraq or Syria, in a ritual reminiscent of similar celebrations by Palestinian terrorists following deadly attacks against Israeli civilians.

A blond-haired, Russian-speaking terrorist then addresses the camera, once again congratulating ISIS's "Sinai Province" branch for "downing the plane of the Russian infidel Crusaders."

"We say to them: We are with you, we love you, and we will complete what you have begun," he continues, vowing to drive Russian forces out of Syria and then attack Russian soil.

Then, wielding a dagger, he points at the camera and warns the Russian President: "Putin, you swine... you and your people will regret your actions."

"Allah willing, we will reach every one of you."

"We will not  make do with downing your planes," he added. "We will attack you in your own lands, we will crush you, we will slaughter you and finish you off."

"You will be defeated, and you will pay dearly for coming to our countries."

Justifying the downing of the plane, which killed all 224 people on board, the terrorist drew a comparison with Russian airstrikes in Syria, some of which are targeting ISIS-held areas.

"Just as you bombed our innocent people with your planes, we struck your plane and killed 240 (sic) of your own people."

The video did not, however, include details of how ISIS allegedly caused Metrojet Flight 9268 to crash.

Experts say the plane was traveling too high to have been hit by the MANPAD shoulder-launched anti-aircraft missiles Sinai Province is known to possess, and US officials have said the plane crashed after a "flash or explosion" in the air, indicating possible a bomb planted on board.

Investigators are still examining the black boxes to ascertain the cause of the tragedy.