The "Islamic State" (ISIS) terrorist group said Wednesday it had killed a Chinese and a Norwegian hostage, as French and Russian air strikes on its Syrian stronghold were reported to have left 33 fighters dead, AFP reports.

Its English-language Dabiq magazine featured graphic photos of two bodies that appeared to be Chinese hostage Fan Jinghui and Norwegian Ole-Johan Grimsgaard-Ofstad.

A stamp-like caption overlaid on the full-page photo read, "Executed after being abandoned by the kafir (disbeliever) nations and organisations." It was unclear when, where, or how they were killed, but their heads were bloodied by apparent gunshot wounds.