Russian military intelligence is seeking to cause "mayhem" across Britain and Europe, the UK's domestic spy chief said on Tuesday, while a growing threat from al Qaeda and Islamic State was his greatest terrorism concern.
In an annual speech, Security Service (MI5) Director General Ken McCallum also accused Iran of being behind "plot after plot" on British soil.
McCallum said state threat investigations were up 48% in the last year as Russia and Iran turned to criminals, drug traffickers and proxies to carry out their "dirty work".
"It will be clear to you that MI5 has one hell of a job on its hands," he said.
The terrorist trend which the spy chief said concerned him most was a worsening threat from al Qaeda, seeking to capitalise on the conflict in the Middle East, and especially Islamic State, which had resumed efforts to export terrorism, citing the attack on a Moscow concert hall in March.
But so far the conflict in the Middle East had not yet translated at scale into militant violence at home, he said.
Of those people being investigated for involvement in terrorism, 13% were under the age of 18, a threefold increase in the last three years, he said.
Much of McCallum's speech, however, was taken up with the state threats posed by Russia and Iran.
Despite the expulsion of more than 750 Russian diplomats from Europe since Russia invaded Ukraine and the ejection of the last Russian military intelligence officer from Britain earlier this year, he said it was "eye-catching" how Russian state actors were turning to proxies to do their work.
"The GRU in particular is on a sustained mission to generate mayhem on British and European streets: we've seen arson, sabotage and more. Dangerous actions conducted with increasing recklessness," he said, declining to give further details.
Since January 2022, he also said his service and the police had responded to 20 Iranian-backed plots, which potentially posed lethal threats to UK citizens and residents.
"We've seen plot after plot here in the UK, at an unprecedented pace and scale," he said.
