© Alexandr Maksimenko / Sputnik

Russian investigators have launched criminal cases against several leaders of the Ukrainian radical group Right Sector, saying that they possessed evidence of extremism and numerous crimes against Russian citizens and institutions.The Russian federal law enforcement agency specializing in very serious cases - the Investigative Committee - released a press statement on Friday saying that its own department for war crimes along with Russia's Interior Ministry and Federal Security Service obtained evidence against members and leaders of the Right Sector extremist group. Right Sector activities have been banned in Russia since late 2014.The agency reported that on the basis of this evidence, they have initiated criminal cases against Right Sector leaders Dmitry Yarosh, Andrey Tarasenko, and several other top members of the group on charges of extremist activities - a crime that is punished with up to eight years in prison.The Investigative Committee reported that since 2014, about 5,000 members of the Right Sector have been planning and committing various crimes against the Russian Federation, its citizens and its diplomatic missions in Ukraine as well as against Russian-speaking citizens of Ukraine. They also emphasized that these crimes were committed with the silent approval of the Ukrainian authorities.The Right Sector is a federation of radical Ukrainian nationalists which was formed in 2013 out of football supporters' clubs, known in Ukraine as 'ultras.' While officially declaring their ultimate goal to be the foundation of the Ukrainian national state through revolution, in the early stages of their existence the radicals agitated for EU integration and severing all ties with Russia. Right Sector radicals formed the core of the Maidan protests in Kiev, which eventually led to the ousting of democratically-elected Ukrainian President Viktor Yanukovych and subsequent military conflict in the southeastern part of the country.In March 2014, the Russian Investigative Committee initiated criminal cases against several members of radical Ukrainian groups over charges of fighting against the Russian military in the Chechen wars of the 1990s. Right Sector's Dmitry Yarosh also faced a separate criminal case over public calls for extremist activities.In November 2014, Russia's Supreme Court ruled in favor of a lawsuit filed by the Prosecutor General's Office and branded the Right Sector and the Ukrainian National Assembly - Ukrainian People's Self-Defense (UNA-UNSO) groups as extremist, banning them from all activities on Russian territory, as well as from distribution of propaganda and public demonstration of their symbols. Several similar organizations, such as the Ukrainian Insurgent Army (UPA) and Stepan Bandera Trident were also tagged as extremist and banned in Russia.