Britain’s 130,000 police officers were urged to be “vigilant for their personal safety” after counter-terror chiefs warned the threat level against them had increased in the past 24 hours.
Mark Rowley, the national lead for counter-terrorism at the Association of Chief Police Officers, refused to discuss specific intelligence but confirmed the threat level against detectives and support staff up and down the country had been “heightened”.
Police and the intelligence agencies are working around the clock to track hundreds of suspected British jihadists as they return from fighting with Islamic State (Isis) militants in Syria and Iraq.
Assistant Commissioner Rowley said: “The threat level to police officers and staff has been heightened, but we are used to confronting risk and danger; this is what we do on a daily basis, and we are well trained.
“We are informing our officers and staff of the heightened risk and reminding them to remain vigilant and alert to any possible dangers. We are asking them to follow existing policies and good practice. Measures are being put in place to increase the vigilance of officers and staff.
“You will see no major changes in the way we continue to police the UK and engage with our communities – our emphasis is on vigilance.”
In August Theresa May, the Home Secretary, announced the national threat level had increased from “substantial” to “severe”, meaning a terrorist attack is “highly likely”.
Tensions are running particularly high since several Western hostages – including two British men, David Haines and Alan Henning – were murdered by Isis militants.
On Tuesday, Scotland Yard arrested five people during an investigation into a suspected terror plot targeting London.
Friends of those arrested – three of whom attended Westminster City School – have issued messages of support on Twitter proclaiming their innocence.
Tarik Hassane, 21, a medical student known as “The Surgeon”; Gusai Abuzeid, 21; and Rawan Kheder, 20, were seized what security sources described as an intelligence-led operation, including months of surveillance.
Tonight, it emerged that a Baikal handgun, ammunition and silencer were recovered some weeks ago during a raid in north-west London involving detectives from the Trident anti-gang squad.
Friends of one of the men arrested told the London Evening Standard he had until recently lived with his family in north London. Neighbours described him as a “normal boy with loads of friends. It would be a big shock if he has done anything wrong.”