The Islamic State group's second in command has been killed in a US raid in Syria, Pentagon chief Ashton Carter confirmed Friday, in a move he said  would hamper the operational ability of the jihadists.

"The removal of this ISIL leader will hamper the ability for them to conduct operations inside and outside of Iraq and Syria," Carter told reporters of the death of Abd ar-Rahman Mustafa al-Qaduli, referring to him as Haji Imam and saying he served as finance minister for the group.