Neo-fascist fight clubs, which are a global locus of neo-nazism, have caught the eye of western intelligence agencies that consider them a burgeoning national security threat, according to experts and government documents reviewed by the Guardian.

“Active clubs”, pseudo mixed martial arts gangs preaching a strain of far-right activism inspired by the teachings of Adolf Hitler, are well known to be moving across borders. But the revelation that official security services are keeping watch over them, the same kind of agencies known to surveil proscribed terrorist organizations like the Islamic State, shows how active clubs are an evolving and quickly growing threat.

“Intelligence agencies want to be aware of extremist networks that exist in their countries,” said Joshua Fisher-Birch, a terrorism analyst at the Counter Extremism Project, about active clubs, “their potential for current or future violence, and what links they may have to other movements and individuals, both domestically and internationally.”