MOSCOW: Russia said Wednesday its security forces swept up 19 suspected Islamists during coordinated raids across the North Caucasus and annexed Crimea, seizing weapons and explosives including a suicide belt.

The FSB security services said the detainees were members of a group called Takfir wal-Hijra and that it is ultimately working to establish a so-called caliphate, or Islamic state.

"Besides spreading ideological propaganda and recruiting new followers, they were plotting acts of sabotage and terror attacks in the North Caucasus," the FSB said.

During raids in four regions including Crimea, the FSB domestic intelligence agency said it had confiscated copies of extremist materials, explosives including a suicide belt and automatic machine guns.

It told Russian news agencies the detainees were charged with organising and participating in activities within an extremist group.

Russian authorities routinely announce operations to snuff out suspected Islamist cells, particularly in the south of the country and the Muslim-majority republic of Chechnya.

The region's authoritarian head, Ramzan Kadyrov, is accused by rights groups of using the threat of Islamism to stamp out dissent.

President Vladimir Putin's ruthless war against Islamist insurgents in Chechnya in 1999 helped fuel the local strongman's initial popularity.