Britain’s counter-terrorism police are managing around 800 live investigations, with hostile state activity linked to Iran and Russia rising by 50 per cent over the past year, according to Counter Terrorism Policing chief Assistant Commissioner Laurence Taylor.

The disclosure highlights the growing pressure on the UK’s security services as they respond to an increasingly complex mix of terrorism, espionage, cyber threats and foreign interference.

“It does feel like our caseload is like juggling,” Mr Taylor said, warning that officers cannot afford to “drop one of those balls” as investigations expand across multiple threat areas.

In just the last two weeks, we have been facing down an incredibly complex threat picture.

“We’re seeing fundraising for terrorism purposes. We’re seeing overseas travel or certainly intent to travel overseas with terrorism intent.

We’re seeing increased ambition from Islamist groups, to lone individuals accessing extreme right-wing terrorism content online.

He warned: “It feels very much like we’re on a knife-edge of extremism and polarising language that’s cutting through society, and that is leading to our doorstep in counter-terrorism policing.

“To be really clear, we do not and will not tolerate those involved in terrorism in any form, or working on behalf of a foreign state, whether they know it or not.

“And we will do all we can to stop them and bring them to justice.”

Alongside hostile state activity, police are tackling Islamist extremism, far-right radicalisation, terrorist financing and individuals seeking to travel overseas for extremist purposes.

Mr Taylor said global conflicts are increasingly driving domestic security risks, adding that Britain is experiencing heightened social polarisation and rising antisemitism linked to international events.

Taylor said: “What plays out abroad will always have a link back to our shores and the type of threats that we are dealing with.

“And we’re seeing that in global instability now.

And probably one of the clearest examples of this has been the rise in anti-Semitism, an anti-Semitic incident on our streets.”

The warning comes after the Government introduced tougher national security legislation, including prison sentences of up to 14 years for individuals acting on behalf of hostile foreign states.

Britain remains at the Severe terrorism threat level, meaning an attack is officially assessed as highly likely.

The latest figures underline how the UK’s national security priorities are expanding beyond conventional terrorism to include state-backed espionage and hybrid threats, increasing demands on policing, intelligence agencies and public resources.