The new ISIS leader was one of its ideologists,  Amir Mohammed Abdul Rahman al-Mawli al-Salbi, The Guardian reported.

"The Guardian has learned that Salbi was named leader hours after the death of Abu Bakr al-Baghdadi in October. The name that the group gave for Baghdadi’s replacement at the time, Abu Ibrahim al-Hashimi al-Quraishi, was a nom de guerre not recognised by other senior leaders or intelligence agencies," the source noted.

According to the UK source, the former and current ISIS leaders back in 2004 met in Camp Bucca prison in southern Iraq, where both were prisoners.

Amir Abdul Rahman was reportedly appointed the new leader a few hours after the liquidation of his predecessor. The publication writes that now he is trying to unite the leadership of the group, which at the moment is almost entirely composed of terrorists who joined the ISIS in the later stages of its existence.

The Guardian's side say the new leader of the group has connections in Turkey, where his brother is a representative of the political movement.