Terrorists affiliated with Islamic State militants or other extremist groups are expected to attempt another large-scale terrorist attack in Europe and are likely to again target France, the European Union's law enforcement agency said in a report on Monday.
"There is every reason to expect that IS, IS-inspired terrorists or another religiously inspired terrorist group will undertake a terrorist attack somewhere in Europe again, but particularly in France, intended to cause mass casualties among the civilian population," the Europol report said, using the acronym for Islamic State.
Islamic State claimed responsibility for the November 13 terrorist attacks in Paris, which left 130 people dead and hundreds injured. At least 10 attackers are believed to have simultaneously targeted a concert hall, football stadium, cafes and bars in the French capital.
New attacks could be carried out "in the near future," the Europol report said, while also noting that it is "nearly impossible to exactly predict when and where the next terrorist attack will take place and what form it will take."
"Intelligence suggests that IS has developed an external actions command trained for 'special forces style' operations abroad," the report noted. "Central command in Syria is believed to map out a general strategy, but leaves tactical freedom to local leaders."
The Netherlands-based Europol released the report as it launched a new European Counter Terrorism Centre that is meant to assist with major terrorism investigations, encourage information-sharing between national intelligence authorities, and help track terrorist groups' online propaganda and financing flows.
The centre, which currently has a staff of 40 counter-terrorism experts, is already working with French and Belgian authorities on the investigation into the Paris attacks, Europol Director Rob Wainwright said.
Islamic State is not the only threat facing Europe. The Europol report noted that the al-Qaeda terrorist group may be "triggered to put words into action by competing with IS."
There have been concerns that terrorists may be infiltrating the migration flows currently coursing through Europe, but Europol said it has "no concrete evidence" of such a phenomenon.
It underlined, however, that Syrian refugees may be vulnerable to radicalization once they are in Europe, noting that "refugee centres are being specifically targeted by Islamic extremist recruiters."
The report also found that a "large proportion" of Islamic State recruits have criminal records, while a "significant proportion" had been diagnosed with mental problems.
Foreign fighters - Europeans who have fought alongside extremists in Syria and Iraq and return home radicalized - have long been of particular concern to the European Union. They are believed to number around 5,000.