An Internet video released today purports to show an Islamic State group fighter beheading British hostage Alan Henning.
The video mirrored other beheading videos shot by the Islamic State group, which now holds territory along the border of Syria and Iraq.
The video ended with an Islamic State fighter threatening a man they identified as an American.
"Obama, you have started your aerial bombard of Shams (Syria), which keep on striking our people, so it is only right that we strike the next of your people," a masked militant said.
British Prime Minister David Cameron tweeted his condolences to Mr Henning's family.
The brutal murder of Alan Henning by ISIL shows just how barbaric these terrorists are. My thoughts are with his wife and their children.— David Cameron (@David_Cameron) October 3, 2014
This is the fourth such video released by the Islamic State group. The full beheadings are not shown in the videos, but the British-accented, English-speaking militant holds a long knife and appears to begin cutting the three men, American reporters James Foley and Steven Sotloff and British aid worker David Haines.
Henning, 47, nicknamed "Gadget," had joined an aid convoy and was taken captive on December 26, shortly after crossing the border between Turkey and Syria.