A video has been released on the internet by the jihadist group ISIL which it is claimed shows the British aid worker Alan Henning being beheaded.
The extremists had been holding him since last December when he went to Syria to help the relief effort.
ISIL had threatened to kill the Briton in a video showing the execution of British hostage David Haines.
Earlier this week Alan Henning’s wife had appealed for his release.
According to the SITE monitoring group the latest video also shows an American aid worker who is being held hostage.
Britain said on Friday that if a video showing the beheading of British citizen Alan Henning by ISIL militants fighting in Iraq and Syria was genuine, then it was a disgusting murder.
“We are aware of the video and are working urgently to verify the contents,” a spokesman for the British Foreign Office said.
“If true, this is a further disgusting murder. We are offering the family every support possible; they ask to be left alone at this time.”