Balkan countries such as Bulgaria and Croatia are an "important link" in the activity of terrorists in Europe, Newsweek Serbia says in a recent investigation, citing data from French police and intelligence sources.

"States like Croatia and Bulgaria are... not at the center of attention of those who deal with terrorism. At the same time, terror attacks are planned there, and participants go through these states unnoticed," the media outlet quotes information from "materials of French police and secret services".

Basing their information on the documents, they argue Salah Abdeslam, who was arrested in relation to the Paris attacks of November and whose cell appears to have been behind the Brussels attacks, frequently dialed Balkan numbers.

Abdeslam and his affiliates often made their calls using SIM cards from Morocco, Turkey and Belgium, but also Croatian, Albanian and Bulgarian ones. "Serbia[n numbers], at least officially, are not there, but experts advise it should not be considered that this world problem goes around us," Newsweek adds [SR].  

According to the materials which it claims to have obtained, recruits of the so-called Islamic State (IS) group are using the Balkans for "training and to test their endurance and determination to join the terrorists".

Serbian security agency officials are reported as telling Newsweek that the attacks in France and Belgium and calls made by the terrorists show "the Balkans [are] an important link" in terrorist activities.

The same sources, however, say it is "early to disclose operative data".

Dragan Simeonovic, a political science professor and anti-terrorism expert, is quoted as saying that "all important terrorist attacks had links to the Balkans".