MI5 has foiled more than 40 terror plots since the Manchester Arena attack

The boss of MI5 has described the rise of children being investigated for terrorism in the UK as "staggering" as he warned of "canny online memes" drawing them into extreme right-wing ideologies.

Director-general Ken McCallum said the security agency was seeing "far too many cases where very young people are being drawn into poisonous online extremism".

In a wide-ranging speech, he also highlighted the "worsening threat from al Qaida and in particular from Islamic State" - which he said had "resumed efforts to export terrorism" and told how MI5 was "powerfully alive" to the risk tensions in the Middle East posed to terrorist activity in the UK.

Speaking at the Counter Terrorism Operations Centre in west London on Tuesday, he said: "Sadly, 13% of all those being investigated by MI5 for involvement in UK terrorism are under 18.

"That's a threefold increase in the last three years. Extreme right-wing terrorism in particular skews heavily towards young people, driven by propaganda that shows a canny understanding of online culture."

Answering questions from reporters, he said the proportion - one in eight of the people MI5 was investigating for involvement in UK terrorism - was "quite a staggering thing", adding: "That's not something I would have expected to see earlier in my own career."

Reiterating concerns he has previously raised about the role of the internet being the "biggest factor" driving the trend, he described how easily youngsters could access "inspirational and instructional material" from their bedrooms.

Most are influenced by a range of extreme right-wing ideologies, he said, adding that "canny online memes" were drawing children into such views.

"It's not really a consistent single ideology on the extreme right-wing side, and that is what has skewed the numbers most heavily," he said.

Overall, MI5 and the police had disrupted 43 late-stage attack plots since March 2017 saving "numerous lives" he said, adding: "Some of those plotters were trying to get hold of firearms and explosives, in the final days of planning mass murder."

Mr McCallum said MI5 was "powerfully alive to the risk that events in the Middle East directly trigger terrorist action in the UK" and while the "ripples from conflict in that region will not necessarily arrive at our shores in a straightforward fashion; they will be filtered through the lens of online media and mixed with existing views and grievances in unpredictable ways".

Although police had responded to "rising public order, hate crime and community safety challenges, we haven't - yet - seen this translate at scale into terrorist violence", he said, adding: "The overarching UK terrorist threat level remains at substantial - an attack is likely - and is kept under constant review."

Mr McCallum said the terrorist trend that concerned him most was the "worsening threat from al Qaida and in particular from Islamic State", adding: "Islamic State is not the force it was a decade ago. But after a few years of being pinned well back, they've resumed efforts to export terrorism."

And in the last year, he said the number of state threat investigations - inquiries into plots by hostile states - had surged by 48%.

Russia and Iran had turned to employing criminals and private intelligence officers in the UK to do their work on British soil.

MI5 had responded to 20 Iran-backed plots since January 2022, that presented potentially lethal threats to British citizens and UK residents.

Russia's intelligence service had worked to cause "mayhem" in the UK in light of British support for Ukraine in the war between the two nations.

"The UK's leading role in supporting Ukraine means we loom large in the fevered imagination of (Russian president Vladimir) Putin's regime, and we should expect to see continued acts of aggression here at home," he said.

"The GRU (Russian military intelligence) 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 and having precisely the opposite effect of what the Russian state intends in driving increased operational co-ordination with partners across Europe and beyond."

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