That estimate was made public in the meeting Wednesday of senior police officers from more than 35 countries held in the Spanish town of Maspalomas, on the Atlantic island of Gran Canaria.
Interpol's Deputy Director General for Counter-Terrorism Juan Francisco Heras said 800 jihadi fighters have been identified by Interpol, although he estimated the actual number of jihadis operating in the region to be much higher, around 15,000 members.
In fact, it is believed that 1,000 Islamic State (IS) recruits originate from France alone, in addition to about 500 Britons, 250 Australians and 200-250 Germans, according to Heras.
It is also believed that at least 39 Spaniards have been recruited by jihadi groups, according to figures provided by Interpol and Spanish police.
Overall, the figures show why this phenomenon has received so much attention from national security authorities in most Western countries.
They are concerned not solely by the terrorist activities committed by those citizens outside their borders, but also of the possible security threats they pose once on their return to their he countries of origin.