Russia has launched criminal case against the leader of Ukraine's Svoboda party, Oleh Tiahnybok, and some members of Ukrainian National Assembly-Ukrainian People's Self-Defense (UNA-UNSO), accusing them of organizing an armed gang, Investigative Committee spokesman Vladimir Markin told Interfax on Friday.

Markin said Tiahnybok supported Chechen separatists in the 90s.

"Depending on the role of each of them, they are suspected of crimes punishable under Article 209 of the Criminal Code of the Russian Federation - 'formation of a stable armed group (gang) with the objective of assaults, leadership of such a group (gang), and participation in assaults committed by it.'" Markin said.

He said investigators of a battle in Chechnya between the 76th Pskov Airborne Division and Chechen separatist forces led by Shamil Basayev and Khattab had obtained evidence that the separatists who fought Russian troops in 1994-1995 included a unit made up of UNA-UNSO members.

Markin said the unit had been led by brothers Oleh and Andriy Tiahnybok, Ihor Mazur, Valeriy Bobrovych, Dmytro Korchynsky, Dmytro Yarosh, Volodymyr Mamalyha, and others who had not been identified.

The spokesman said the Investigative Committee's North Caucasus branch had collected enough evidence to charge them and issue arrest warrants for them.