MI5 Andrew Parker
© Daily Mail'Britain is facing an unprecedented threat of terror today.'
Andrew Parker warned that activity from sick terrorists is harder than ever to detect, and there has been a "dramatic upshift" in the type of threats seen. In interviews with Sky News and the BBC he said that it was the highest threat he had seen in his 34-year career at MI5.

Mr Parker revealed that 20 attacks on British soil had been thwarted in the past four years - including SEVEN in as many months. And he revealed that 130 Brits who had travelled to Iraq and Syria to fight for so-called Islamic State had died - with around 800 in total leaving for the area.

The top boss said: "Today there is more terrorist activity, coming at us more quickly, and it can be harder to detect. He went on: "We're now running well over 500 live operations involving around 3,000 individuals known to be currently involved in extremist activity in some way.

"As well as those we are looking at today, risk can also come from returnees from Syria and Iraq and also the growing pool of over 20,000 individuals we've looked at in the past in our terrorism investigations. "And there will be some violent extremists not yet known to us at all."

He admitted that it was not possible to be "perfect" and stop all attacks, because they can go from "inception through planning to action in just a handful of days".

Mr Parker also paid tribute to the 4,000 MI5 staff working on hundreds of operations. He said that whenever an attack happens, everyone was "deeply affected, on a personal and professional level".

And he hit out at tech companies for failing to do enough to help counter terrorism - saying they have an "ethical responsibility" to do more. He said: "All those (technological) developments that we have give opportunities at the edges to terrorists."

Some action is being taken and they were "not the enemy", but the pace of change was so quick that the firms needed to stay on top of their game.