"Up to 5,000 EU citizens joined Islamic State"

"Up to 5,000 EU citizens joined Islamic State"

LONDON -- Europol Director Rob Wainwright has said that the continent is facing its "greatest security threat in more than a decade."

This is because "as many as 5,000 EU citizens have joined fighting in Syria" and could pose a risk to their homelands if they return, Reuters reported.

Wainwright referred to September 11, 2001 attacks on the Unites States as the previous security crisis for Europe.

"It is certainly the most serious terrorist threat Europe has faced since 9/11," Wainwright told a British parliamentary committee

He told the committee that between 3,000 and 5,000 EU nationals could come back "with the capability, or the intent and capacity, to carry out operations similar to the Paris attacks" last week, and that his agency had collated a database of 2,500 suspects.

"One of the important evolutions we're seeing right now in the current terrorist threat is the way the internet is used, clearly much more aggressively, much more imaginatively by the networks," he said, and advised "closer and more productive cooperation" between authorities and IT companies.