Terrorists could use biological weapons created using artificial intelligence to target Britain, the head of MI5 has warned.

Director General Sir Ken McCallum said among the potential ways that humans could misuse AI, bioweapons are a key concern.

The security service chief gave his annual threat speech in Thames House on Tuesday morning, where he said the agency’s state threats caseload has quadrupled in the past 10 year.

“In 2026, MI5 is devoting more resource to countering state threats than during the Cold War”, he said.

Here are the key points from his speech:

AI has significantly changed the way Britain must respond to terrorism, as well as the dangers it faces from it.

Sir Ken announced that MI5 had launched the AI Threat Assessment Centre (AITAC) to help manage the risks thrown up by the misuse of AI.

While Sir Ken acknowledged that the full threat has not yet been realised, it has the “potential to change the stakes on existing or even new bioweapons”, he said.

“These risks are real”, said in his speech.

The UK Intelligence Community - MI5, GCHQ, MI6 - is working closely with the UK’s globally respected AI Security Institute to take them on.”

Following his address, he added: “It is the case that of all the various human misuse of AI, the one that has me and colleagues particularly focused, alongside the all the other ones I’ve listed misinformation, radicalisation and serious crime, bioweapons is an area where the Government is taking additional step,” he said.

“In the case of bioweapons one concern would be that comparatively low sophistication actors may have the capability in the AI era if these guardrails do not function as intended.

“So for the last 25 years, if you look at where Al Qaida was around 9/11 it has long been the case that many terrorists would dearly love to have some kind of capability around chemical or biological weaponry. But that hasn’t been easy for them to achieve. One risk is that AI could be enable dangerous knowledge to get into the hands of people we would all rather didn’t have that knowledge.”

Russia remains “aggressor number one” as Putin’s Kremlin continues to lash out at the UK and its allies, Sir Ken said.

Russian authorities are using tactics that stop just short of conventional conflict to “unsettle” European nations when their “military progress in Ukraine is minimal and horrifically costly”.

The Kremlin is “scrambling” to pay criminals or exploit naive volunteers to do their bidding after seeing almost 1,000 of its representatives ejected from allied countries since the full-scale invasion of Ukraine was launched.

Iran is another nation keen on “subcontracting its UK violence”, Sir Ken said.

This year, Iranians have attempted to “expand their hybrid campaign”. Over the last 12 months more than 50 people have been arrested in Iran-linked operations here in Britain.

Sir Ken said that much of the state’s aggression has been aimed at British Jewish communities as he highlighted a wave of assaults that took over the summer, including the arson attacks on four Hatzola ambulances in Golders Green by an IRGC-backed group calling itself the Islamic Movement of the Companions of the Right.

The Director General did not directly mention the recent arrests over a suspected terror plot at RAF Fairford but said Iran has also shifted to harder targets in recent months, such as military sites.

MI5 also remains focussed on the threat from China, which continues to conduct espionage, coercion and democratic interference.

Just two weeks ago, the agency issued an espionage alert to the academic community warning that agitators posing as a conventional research body has been funding projects linked to AI and cybersecurity in the UK.

In recent years “determined efforts” have degraded the leadership of Islamic State but Al Qaida and ISIS continue to “direct and inspire” attacks.

“MI5 is still having to respond to attempts to carry out mass casualty attacks in the UK”, Sir Ken said.

However, it is the rise of extreme rightwing terrorism that has seen the threat level raised to “severe” in Britain.

Anti-immigration and anti-Muslim grievances are increasingly “tipping into terrorist intent”, he warned.

Community cohesion has become a national security front line, he said, with Britain’s enemies aiming to sow division.

“Those who mean us harm are trying – often with a helping hand from polarising algorithms – to divide our communities and turn us against one another.

“The sharpest form this takes is lethal violence. We were all horrified by the murder of Ann Widdecombe in July.

“The individual facing trial has no also been charged with terrorist offences against the leader of Reform UK.

“With the prosecution pending, I’m limited in what I can say. But sadly the case is part of a concerning trend of violence targeted at political figures, religious or community groups and more.”

Sir Ken also used his speech to issue a rallying cry to the British public to be prepared to play a part in protecting national security and boosting resilience.

He set out three key areas: systemic resilience of the UK’s critical infrastructure, societal resilience in terms of cohesion, and technological resilience.

Sir Ken said: “Today I want to talk directly to the British public.

“When you hear national security don’t just think of Ukraine, subsea cables, armed drones or cyber weapons.

“Think of the place where you live, where you work.

“Think of a flicker in the power grid supplying your home. Think of your local synagogue or mosque having to install enhanced security measures.

“Think of a toxic or manipulative post on social media. Think perhaps of what online algorithms are feeding your teenagers in their bedrooms.

“We all have a stake in our national security.”