Secretive Egyptian cleric Abu Osama al-Masri, 42, has been named by Western intelligence chiefs as the prime suspect behind the attack on Metrojet Flight 9268 which killed all 224 on board.

In this footage believed that Abu Osama al-Masri is talking about his group victories against Egyptian army in the group propaganda video.

He is leader of Sinai Province – formerly known as Ansar Bayt al-Maqdis – which swore allegiance to ISIS chief Abu Bakr al-Baghdadi last year and has targeted Egyptian soldiers and police since the military coup toppled President Mohamed Mursi after mass protests two years ago.

The secretive 42-year-old cleric studied at Al-Azhar, a 1,000-year old Egyptian center for Sunni Islamic learning.

In recent years he took up arms in Sinai before heading to Syria with about 20 followers when security forces clamped down on extremist after Mursi's departure. 

There, he and the other fighters gained experience that would prove useful upon their eventual return to the Sinai, when they were approached by ISIS and embraced its goal of creating a caliphate across the Muslim world.