The Ukrainian Interior Ministry says it has opened criminal proceedings against Russian Defense Minister Sergei Shoigu and Russian oligarch Konstantin Malofeev for "aiding terrorists," it says in reference to alleged ties to Ukrainian separatist groups.
The ministry's website says Shoigu is being investigated for organizing illegal armed groups in eastern Ukraine that are responsible for attacks on Ukrainian authorities and seizures of government buildings, for killing of people and for other serious crimes.
The investigation comes just over a month after Russia launched an investigation of its own against Ukraine's Interior Minister Arsen Avakov and a billionaire local governor over the killings of civilians and journalists in conflict-torn east Ukraine.
Avakov, who on Tuesday announced the move against the two Russians, said in a statement that Shoigu is suspected of having organised the "illegal armed groups on Ukrainian territory".
Malofeev is being investigated for his role in financing those groups.