Advances in technology are allowing terrorists to communicate “out of the reach of authorities”, the head of MI5, Andrew Parker has told the BBC.
The serving boss of the UK’s home security agency told Today it was becoming more difficult to obtain online information.
He said internet companies had an “ethical responsibility” to alert agencies to potential threats.
But MI5 was not about “browsing the lives” of the public, he added.
Ministers are currently preparing legislation on the powers for carrying out electronic surveillance.
But Mr Parker, in the first live interview by a serving MI5 boss, said what should be included in new legislation was a matter “for parliament to decide”.
“It is completely for ministers to propose, and parliament to decide. It’s a fundamental point about what MI5 is. It’s for us to follow what’s set by parliament, and that’s what we do.”
‘Out of reach’
He said online data encryption was creating a situation where the police and intelligence agencies “can no longer obtain under proper legal warrant the communication of people they believe to be terrorists”.
He said it was a “very serious” issue adding: “It’s in nobody’s interests that terrorists should be able to plot and communicate out of the reach of authorities.”
Mr Parker also told the BBC:
- The terrorism threat is the “most serious threat Britain faces in security terms”
- MI5 had to “make choices” about where to put resources, and make sure they were “focused where the sharpest threat is”
- On the killers of Fusilier Lee Rigby: “There cannot be a guarantee that we will find and stop everything. That’s not possible. We can’t monitor them all the time.”
- He rejected the suggestion that security service tactics can lead to radicalisation saying it was “completely untrue”
- He played down fears about extremists entering Europe among the thousands of refugees from Syria
BBC security correspondent Gordon Corera said many intelligence officials would say the challenge was not so much about new powers, but maintaining their existing capabilities against changing technology.
“Of course critics are sceptical about that and say it’s all part of a campaign for new powers,” he said.
“The detail will be in that legislation when we see it.”