The UK's national head of counter-terrorism, Assistant Commissioner Mark Rowley, warned on Monday that evidence shows Islamic State (ISIS) is "trying to build bigger attacks" worldwide, and in Britain in particular.
Speaking at a London briefing, Rowley said a large-scale "spectacular" attack is the "natural next step" for the jihadist group, reports BBC.
ISIS has already pulled off massive attacks, such as the attack on Paris last November in which 130 people were murdered at six coordinated fronts, but now it appears eager to launch more assaults of a similar scale.
Rowley revealed terror-related arrests hit a new record last year, reaching 339 in England, Wales and Scotland. Scotland Yard said the last three years saw a 57% rise in terror-related arrests as compared to the previous three years, and in response the UK terror threat level is currently at "severe."
He said that recently there has been a shift in ISIS from planning smaller attacks to aspirations for large-scale affairs.
"In recent months we've seen a broadening of that. Much more plans to attack Western lifestyle, and obviously the Paris attacks in November. Going from that narrow focus on police and military as symbols of the state to something much broader," Rowley said.
"And you see a terrorist group which has big ambitions for enormous and spectacular attacks – not just the types that we've seen foiled to date."
He said ISIS is looking to infiltrate its terrorists who had military training in Syria over to northern Europe to launch attacks.
The UK counter-terror head added that psychologists are working with counter-terror units over increasing concerns people with mental health problems are being radicalized.
Just last Thursday a German doctor was arrested for brain-washing a mentally ill man and sending him to Iraq where he conducted a suicide bombing for ISIS.