BERLIN (AP) — A top police official says that Germany needs to remain vigilant against the threat of extremist attacks.

Holger Muench, the head of Germany's Federal Criminal Police Office, told reporters on Thursday that "attacks in Germany are possible anytime."

He said the loss of territory by the Islamic State group in Iraq and Syria would lead the group to "increase its efforts to commit attacks, especially in Western countries."

Security authorities in Germany consider 616 extremists potentially dangerous enough to carry out an attack. Of those, about half are currently abroad and of the others who are in Germany, about 100 are in prison.

Since 2012, more than 920 jihadis have left Germany for Syria and Iraq, and about 300 of those have since returned to Germany.