The Sept. 11, 2001, attacks on the US and deadly incidents in Britain made tackling Islamist plots the priority for counter-terrorism police, with resources focused on the threat from home-grown and foreign-based militants.

Matt Jukes, the head of counter-terrorism at London's Metropolitan Police, said there has been a shift in emphasis as foreign states try to corrupt or intimidate people and are involved in murder and kidnap plots in Britain.

“The requirement for us to play a law enforcement part in countering the threats from hostile states is unprecedented,” Jukes told reporters at New Scotland Yard, the Metropolitan Police's headquarters.

Investigations involving state threats have quadrupled in the last the last two years and these cases now account for a fifth of counter terrorism officers' times, he said.

Iran has made at least 15 attempts to kidnap or even kill British nationals or individuals based in the UK regarded by Tehran as a threat, Jukes said.

Last year, British Foreign Secretary James Cleverly summoned Tehran's most senior diplomat over alleged threats by Iranian security forces to journalists in Britain.

The Iranian embassy in London did not immediately respond to a request for comment.

Jukes said police were making inquiries after claims China last year was operating “police stations” in major cities around the world, including New York. China has denied the allegations.

Britain blamed Russia for a 2018 nerve agent attack targeting former Russian double agent Sergei Skripal and his daughter Yulia in Salisbury, southern England, a charge Moscow has denied. And this week a security guard at the British embassy in Berlin was in a London court accused of spying for Russia.

The Metropolitan Police's War Crimes Team, which is a unit within its counter-terrorism command, is also dealing with more than 100 referrals from Ukrainian refugees in Britain related to the war with Russia, he said.

Despite the shift in focus, counter-terrorism police's biggest job is still tackling terrorism. Jukes said police disrupted eight late-stage terror plots last year and in some cases they have been investigating children as young as 13.