The so-called "Islamic State" has expanded its list of targets from police and military to include large-scale attacks on civilians, London Metropolitan Police Assistant Commissioner Mark Rowley told reporters on Monday.

"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.

The global jihadist group is widening its list of targets from a "narrow focus on police and military as symbols of the state to something much broader," he warned, citing last year's Paris attacks that killed 130.

"Terrorist groups have always wanted to do the grand and the more spectacular attack because it gets more impact," he noted.

Rowley said British police have foiled seven terror attacks since late 2014 to early 2016, and arrested a record number of terror suspects last year.

British authorities have a long-running concern citizens could become radicalized over the internet or return home after receiving training with the terror group in Iraq or Syria.

An estimated 800 British citizens are thought to have joined IS in Syria or Iraq.

Rowley said IS is trying to sneak trained jihadists into northern Europe to carry out attacks.

The UK maintains a terror threat level of severe, the fourth of five levels indicating an attack is highly likely.

cw/jil (AFP, Reuters)