An EU report warns that a third of the estimated 5,000 European nationals who traveled to Iraq and Syria to join Takfiri terrorists have returned home, probably with a mission to launch attacks.

The report, to be presented to EU interior ministers on Friday by the bloc's counter-terrorism coordinator Gilles de Kerchove, said as many as 1,750 Takfiri terrorists may have returned home.

Fifty-percent of the terrorists remain in the battle theater, which amounted to between 2,000 and 2,500 Europeans, while between 15 to 20 percent of those who joined the terrorists have died, the report added.

There were two types of "foreign terrorist fighters" returning, the report said, identifying them as "those in the majority that will drift back, and those who will be sent back on specific missions, which are of most concern."

Even some European women and children born or raised in areas under the control of Daesh could present a security threat as they may have been influenced by the group's Takfiri ideology, it added.

Some returnees have been convicted and serving prison sentences, while some others are being carefully monitored and some are free in their communities, the report said without giving any figures.

Last month, Belgium warned that Takfiri terrorists were increasingly returning to Europe. Daesh claimed responsibility for March 22 Brussels attacks which killed 32 people. The attackers were linked to November 2015 attacks in Paris, which killed some 130 people.

According to the new report, "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."

It said the European Takfiris remain in touch with Daesh via social media networks, and are greatly migrating from the mainstream Twitter social networking service to Telegram end-to-end-encrypted messaging service.

Director of the department of affairs of the challenges and threats in the Russian Foreign Ministry, Elijah Rogachov

Some 30,000 militants from over 100 countries have reportedly traveled to Syria and Iraq since 2011 to join the ranks of Takfiri terrorist groups.

Eager to see the back of the Syrian government, many European countries initially turned a blind eye to the flow of citizens to the Middle East, ignoring warnings that they would return someday and hit back at home.

On Monday, Russian Foreign Ministry's Elijah Rogachov said more than 3,200 Russian citizens have gone to Syria and Iraq to join terrorist groups there.

Rogachov told Arabic-language al-Baghdadia television network that international terrorist threats have taken on a new form due to the activities of Daesh terror network in recent years.

"The group was initially active in Iraq and Syria, but gradually the threats spread to other countries and regions of the world, like North Africa, South and Southeast Asia as well as Europe, and we feel it now in Russia,” he said.

“According to our estimates, the threat comes from militants of Russian origins who were recruited in Iraq and Syria. There are more than 3,200 Russians present in the conflict zones,” he added.