Russia's security agency says it has arrested five suspects linked to the Islamic State group, who have been preparing an attack in southern Russia.

The Federal Security Service, the main KGB successor agency known under its Russian acronym FSB, said Friday that the suspects were arrested in the town of Pallasovka in the Volgograd region, about 900 kilometers (some 560 miles) south of Moscow.

The FSB said the suspects had weapons and explosives and were involved in trying to recruit local residents for working for the IS.

Russian officials said that 5,000-7,000 residents of Russia and other ex-Soviet nations have traveled to Syria to join IS. Russia has described the extremist group as a security threat and has conducted an air campaign in Syria since September.