Moscow’s counter-terrorism agency, the FSB, said today it had arrested the people in the North Caucasus province of Dagestan.
The FSB said the suspects were preparing attacks with automatic weapons and explosives in crowded places in the Russian capital. They are thought to have been detained in Makhachkala, capital of Dagestan.
Islamist insurgents in Dagestan have mounted frequent attacks on police and officials, and some have sworn allegiance to ISIS.
Dagestan is next door to Chechnya and many Muslim Chechens detest Moscow, especially after two brutal wars (1994-96 and 1999-2000) and occupations by Russian troops.
Russia has waged an air campaign in Syria since September 2015 in support of Syrian President Bashar Assad.
President Vladimir Putin and other Russian officials have admitted thousands of citizens of Russia, including Chechens and others, have joined ISIS in Syria.