Alexander Bortnikov

A high-ranking Russian official has pointed fingers at Ukraine for orchestrating the deadly attack on the Crocus City Hall concert hall near Moscow, which claimed the lives of 139 individuals last Friday, according to a report by AFP.

Russia on Saturday said it had arrested 11 people — including four gunmen — over the attack on a Moscow concert hall claimed by ISIL, as the death toll rose to 133.

Islamic State evolved from the Arab Spring, Russia’s Federal Security Service (FSB) director said in Moscow on Wednesday.

Addressing a meeting of top security officials from ex-Soviet states (CIS) Aleksandr Bortnikov added that Islamic State "gained momentum due to the duplicity of certain world powers."

Two men have been detained over the killing of Boris Nemtsov, a Russian oppositioner who was shot dead late on February 27, Russian officials say.

They are named as Anzor Gubashev and Zaur Dadayev, according to the Federal Security Service (FSB) director Aleksandr Bortnikov.

Bortnikov told Russia's state-owned Pervy Kanal (First Channel) the two are "citizens of the Caucasus."

Russian and international intelligence services thwarted planned terror attacks during the Sochi Olympics, according to the Director of the Russian Federal Security Service (FSB).