Up to 5,000 jihadists are feared to be in Europe after returning from terrorist training camps, the head of Europol has said.
Rob Wainwright, director of the EU-wide law enforcement agency, predicted further attacks by Isis following the massacres in Paris that killed 130 people in November.
“Europe is currently facing its biggest terror threat in more than a decade,” he told Germany’s Neue Osnabrücker Zeitung newspaper.
“One can expect Islamic State (Isis) or other religious terror groups to stage an attack somewhere in Europe with the aim of achieving many casualties among the civilian population.
“Additionally, there is the risk of individual attackers – this has not reduced.”
Europol estimates that there are between 3,000 and 5,000 Europeans who have travelled to terrorist training camps abroad, including those run by Isis in its territories in Iraq and Syria, and returned home.
Several of the Paris attackers slipped back into the continent by using fake documents to pose as refugees, travelling along the well-trodden route via Turkey, Greek islands and up through the Balkans, raising fears that Isis was using the crisis to traffic its fighters.