"The heinous murder of David Haines shows once again how the international community must mobilize against Daesh," the French presidency said in statement, referring to the Arabic acronym for IS, which the presidency said was a vile and cowardly organization.
Islamic State militants fighting in Iraq and Syria released a video on Saturday that purported to show the beheading of British aid worker David Haines, who was kidnapped last year.
On Monday, France will host an international conference on Iraq's security crisis. REUTERS