Former head of MI6: We must now watch everyone to stop terrorism

The security services must watch everyone if they are to continue to prevent terrorist atrocities in the UK, the ex-head of MI6 has warned.

Sir John Sawers said it was not possible to monitor terrorists without intruding upon the lives of ordinary people.

In his first speech since leaving the role, Sir John agreed with with the Prime Minister's belief that there cannot be "no-go areas" online where terrorists can "play their trades".

He also warned that a terrorist attack in the UK is now highly likely.

"Of course there is a dilemma here because the general public and politicians and the technology companies, to some extent, they want us to be able to monitor the activities of terrorists and other evil doers but they do not want their own activities to be open to any such monitoring," Sir John said.

Government Communication Headquarters (GCHQ) on the west of Cheltenham. Credit: PA Wire
David Cameron has pledged to revive the controversial 'snooper's charter'. Credit: PA Wire

"I think one benefit of the last 18 months' debate is that people now understand that is simply not possible and there has to be some form of ability to cover communications that are made through modern technology."

"The prime minister must have been right when he was saying last week that you cannot afford to have complete no-go areas, we cannot have no-go areas in our communities where the police cannot go, because that just allows space room for the evil doers to ply their trades."

Sir John was speaking at the central London launch of the Edelman Trust Barometer, an international survey of public trust in institutions including the security services and other government institutions.

His comments come weeks after the head of MI5 warned that a group of al-Qaida terrorists is planning "mass casualty attacks" against Britain and the West, following the attacks in Paris which left 12 people dead.

In the wake of the atrocities, David Cameron spoke about the need to give security agencies ''robust powers'' to protect the public from extremists.

Mr Cameron has pledged to revive the so-called "snooper's charter", enabling agencies to track emails and other online communications, if he wins power in May's general election.