British authorities launched a hunt on Wednesday for a man with a British accent whose voice featured on an Islamic State (IS) video purporting to show the beheading of an American journalist, as Foreign Secretary Philip Hammond voiced concern about Britons joining Islamist militants overseas, Reuters reported. The voice appeared to come from a masked IS jihadist, dressed in black, who stood next to a kneeling James Foley in the video released online. Hammond said British intelligence services would work closely with the United States to try to identify the man and a specialist counter-terrorism police unit launched an investigation into the contents of the video. But he said he was not surprised to hear the accent as the government has repeatedly voiced concerns about rising numbers of British youths heading overseas to fight in Syria or other conflicts then potentially posing a risk in their home country when they return.