Up to 1,750 ISIS members returning to Europe with 'specific missions,' EU report warns

About 1,750 ISIS members have returned to Europe, and some of them have orders to carry out "specific missions," according to a recent EU report.

Roughly 5,000 Europeans have traveled to Iraq and Syria to join the jihadist group, with about 15 to 20 percent dying on the battlefield. Around 35 percent have returned to Europe, while 50 percent, which is about 2,000 to 2,500 members, remained in the Middle East, Daily Mail reported.

The percentages listed in the report suggests that as many as 1,750 members have returned.

It stated that there are two different types of foreign fighters returning to Europe. "Those in the majority that will drift back, and those who will be sent back on specific missions, which are of most concern," the report revealed.

It warned that some European women and children born or raised in the ISIS caliphate may have been radicalized and could pose a security risk.

The report, which will be presented to the EU interior ministers by EU counter-terrorism coordinator Gilles de Kerchove on Friday, noted that some of the returnees have been convicted and detained while others are being monitored. Some, however, remain free in their communities.

"There is also a significant foreign terrorist fighter contingent with Daesh in Libya which might attempt to use their nationality or family connections to return to Europe," the report continued, using the Arabic acronym for ISIS.

It also revealed that the returnees have remained in contact with ISIS members in the Middle East through social media, and they are increasingly abandoning Twitter for the encrypted one-to-one messaging service Telegram.

On Oct. 30, the head of the German Federal Office for Protection of the Constitution (BfV), Hans-Georg Maassen, warned that the success of the operations against ISIS in Syria and Iraq could lead to attacks in Europe.

Reacting to the operation against the militant group in Mosul, Maassen said: "That is good. But this can lead to the consequence that this situation may alert its [IS] supporters in Europe, that it can lead to violent attacks."

ISIS has claimed responsibility for multiple terrorist attacks in major European cities over the past year and a half. In some cases, the perpetrators either pledged allegiance to ISIS or have been directed by the jihadist group, including through social media.