Russia's top security agency says it is investigating 1,600 individuals and organizations suspected of aiding the Islamic State militant group.
Alexander Bortnikov, director of the Federal Security Service, the main successor to the KGB, also said on December 15 that his agency has identified 2,900 Russian citizens suspected of involvement in extremist groups in Syria and Iraq.
He said that 198 of them have been killed in fighting and another 214 have returned to Russia. Bortnikov added that 80 of those who have come back have been convicted and another 41 have been arrested.
President Vladimir Putin has said previously that between 5,000 and 7,000 citizens of Russia and other ex-Soviet nations have joined IS. He said the Russian air campaign in Syria has been aimed at protecting Russia's security.
Bortnikov said the threat from IS has actually picked up, as expected, since Russia started its bombing campaign in Syria.
"Militants from the 'hot spots' are trying to penetrate," prompting the agency to increase its efforts to prevent attacks, he said.
