Photo taken on March 19, 2017 shows Iraqi Emergency Response Division soldiers who fight with Islamic State militants in western Mosul, Iraq. (Xinhua/Lefteris Partsalis)

MOSCOW, April 26 (Xinhua) -- Russia's Federal Security Service (FSB) said Wednesday that it has detained two supporters of the Islamic State (IS) in the country's Far East region.

The suspects were plotting a terrorist attack on a mass of people on the Far Eastern island of Sakhalin, the FSB said.

One of the detainees is a Central Asian citizen and the other is a Russian national.

"During searches of their residences, improvised explosive devices, components for their manufacture, IS propaganda materials and other banned extremist literature were seized," it said.

The FSB has launched criminal proceedings against the detainees, establishing the circumstances of their illegal activities and conducting necessary operational and investigative procedures.