Nineteen Islamic extremists plotting terrorist attacks in the North Caucasus have been detained in four Russian regions, the Federal Security Service (FSB) said in a statement on Wednesday.

"The Federal Security Service has exposed an inter-regional extremist community linked to the Al-Takfir wal-Hijra international terrorist organization (outlawed in Russia), whose idea of takfir, or declaration of infidelity, theologically justifies action towards kafirs, or infidels, including Muslims, as well as the need to establish a Caliphate. In February, 19 radicals were detained in Crimea, the Karachay-Circassian, Krasnodar and Rostov regions, who, apart from promoting their ideas and recruiting new supporters, plotted to carry out subversive activities and terrorist attacks in the North Caucasus on behalf of Al-Takfir wal-Hijra," the statement reads.

Extremist literature was seized during searches of their homes and places of their secret meetings, and an arms cache was found in a forest in the Karachay-Circassian region, which contained an RPK machine gun, an AKM assault rifle, ammunition and improvised explosive devices equaling about three kilograms of TNT, including the so-called suicide belt, TASS reported.

"The detained have been charged under Article 282.2 of the Russian Criminal Code (the organization and participation in the activities of an extremist organization). Ten masterminds and active members of the organization have been taken into custody," the FSB said, adding that their activities would be additionally classified following forensic examinations of the weapons.