Moscow on Saturday urged Ukraine to outlaw ultra-nationalist groups after two people were killed in fresh clashes in the Russian-speaking east of the country.
"Bandera structures in Ukraine should be declared illegal as those inciting inter-ethnic hatred," Konstantin Dolgov, the Russian foreign ministry's human rights pointman, said on Twitter.
Stepan Bandera was a leader of the Ukrainian nationalist movement accused by Russians of siding with Nazis during World War II.
"No one abolished Ukraine's duty to counter racism, racial discrimination and xenophobia. That should be fulfilled," Dolgov added.
Two people were killed in Ukraine's Russian-speaking city of Kharkiv when nationalists opened fire on a group of men trying to storm their headquarters late on Friday.
Several people were also injured in the gun fire. The nationalists surrendered, and police said they made 30 arrests.
"Arresting neo-fascists in Kharkov should mark the beginning of large-scale activities to neutralise and punish the extremists who are getting out of hand," Dolgov said, using the Russian name for the city.
On Friday, Moscow said it reserved the right to protect compatriots in the whole of Ukraine, suggesting it could move its troops beyond the Crimean peninsula it is now occupying.