Asked if GCHQ could guarantee it does not operate beyond UK law, Sir Iain Lobban replied: "I can give you that guarantee. I believe that to be true. We are subject to the law."
MI6 chief Sir John Sawers said the leaks from NSA whistleblower Edward Snowden "have been damaging and put operations at risk." The heads of Britain's intelligence agencies were questioned by MPs in public for the first time.