The group calling itself Islamic State has beheaded the American hostage Peter Kassig, according to claims in a video posted online.<br /><br />The film, which euronews is not showing, features an apparent execution carried out by a masked man.<br /><br />The 26-year-old aid worker, a former soldier who had changed his name to Abdul Rahman, devoted his time to helping Palestinian and Syrian refugees.<br /><br />He had written to his parents – who had pleaded directly to his captors to release him – saying if he did die, people should take comfort in the fact he had worked to alleviate suffering.<br /><br />Kassig was working for his own charity SERA – Special Emergency Response and Assistance – when he was captured in October last year.<br /><br />It has stopped operating in Syria because of the security situation.<br /><br />Washington says if the video is authentic, the White House would be “appalled by the brutal murder of an innocent American”.<br /><br />British Prime Minister David Cameron said the apparent beheading again showed ISIL to be a “depraved organisation”.<br /><br />Peter Kassig had appeared in an ISIL video showing the murder of British worker Alan Henning, which was roundly condemned by Muslims.