Agency director James Comey told reporters today that he knew who the militant was but would not be releasing his identity or nationality to the media.The executioner, who has a British accent and has been dubbed Jihadi John, is one of four British jihadis known as the 'Beatles' holding hostages in Syria.He appears in the group’s execution videos wielding a knife – and taunts President Obama before carrying out the killingsToday British officials would not say if the identity had been shared with the authorities on London, and would not be drawn on whether any arrests are imminent.A Home Office spokeswoman said: 'We won't be commenting on matters of security at this stage.' Comey said the FBI believes that ISIS is 'looking to try to do something in the U.S.,' but added he did not believe the group is capable of a sophisticated or complex attack.During questioning from reporters at the FBI headquarters Comey also spoke about Khorasan group, an al Qaeda affiliate who were targeted along with ISIS by American airstrikes in Syria earlier this week.He said he was 'not confident at all' the threat from Khorasan militant group was thwarted by the airstrikes. 'We don't have complete visibility about their activities. 'We believe they've been working toward an attack, but it's hard to say whether it would come tomorrow, in three weeks, or in three months,' he said. Comey added the FBI is still working hard to identify two people in ISIS videos who appear to have American or Canadian accents.'We have a big focus going on that right now,' Comey said.He said about a dozen Americans are believed to be fighting with extremist groups in Syria at the moment.He says more than 100 Americans have either tried to go to Syria and been arrested, gone successfully, or gone and come back.(dailymail.co.uk)Bakudaily.Az