The head of a British intelligence agency has said that some of the Internet companies has been ignoring the way the web is being used by extremists.<br />Robert Hannigan, the head of Government Communications Headquarters, said technology giants such as Google, Facebook and Twitter are "in denial" about groups such as al-Qaeda and the Islamic State of Iraq and the Levant, putting propaganda online with apparent ease. <br />Al Jazeera’s Phil Lavelle reports from Dublin.
