Director general of MI5 Andrew Parker
Revelations such as the claims made by former US intelligence operative Edward Snowden are the gift extremists need ‘to evade us and strike at will’, Andrew Parker claimed.
He added that people mistakenly thought staff at listening service GCHQ would browse at will through people’s private lives.
‘That is, of course, utter nonsense,’ he told the Royal United Services Institute in London last night.
Mr Parker asked if ‘anyone really believed’ terrorists should be free to communicate without spies listening.
The MI5 boss’ comments came after the surveillance activities of GCHQ and its American counterpart the National Security Agency (NSA) were disclosed in the Guardian through a series of leaks by Mr Snowden.
The former NSA employee, who is currently in Russia, leaked information in May that revealed mass surveillance programmes such as the NSA-run Prism and the GCHQ-operated Tempora.
Under the £1billion Tempora operation, Cheltenham-based GCHQ is understood to have secretly accessed fibre-optic cables carrying huge amounts of internet and communications data and shared the information with the NSA.
Mr Parker, who replaced Sir Jonathan Evans, said MI5 needs to be able to read or listen to terrorists’ communications in order to stop them.
‘The converse to this would be to accept that terrorists should have means of communication that they can be confident are beyond the sight of MI5 or GCHQ acting with proper legal warrant,’ he said. ‘Does anyone actually believe that?’
He added: ‘Reporting from GCHQ is vital to the safety of this country and its citizens.
‘GCHQ intelligence has played a vital role in stopping many of the terrorist plots that MI5 and the police have tackled in the past decade.’
Mr Parker continued: ‘It causes enormous damage to make public the reach and limits of GCHQ techniques.
‘Such information hands the advantage to the terrorists. It is the gift they need to evade us and strike at will.’
Defending the service’s role, he added: ‘Far from being gratuitous harvesters of private information, in practice we focus our work very carefully and tightly against those who intend harm.’
Mr Parker said he expect at least one or two serious attempts at major acts of terrorism in the UK every year and it remains the case that there are several thousand Islamist extremists in the country who see British people as a ‘legitimate target’.
The director general, who has been with the security service since the early 1980s, led the agency’s response to the July 7 attacks on London in 2005 as director of international terrorism.