Activists from the group led by nationalist Eduard Limonov have taken responsibility for disrupting a concert in Moscow by legendary Russian rock musician Andrei Makarevich.
Makarevich was performing at Moscow's House of Music on September 25 when a group of people released a gas into the concert hall that made those watching the concert feel ill and forced them to exit the building temporarily.
Limonov's group, which calls itself Other Russia, posted a message on its website claiming responsibility.
The group emerged out of the now-defunct Other Russia movement, a broad opposition coalition that also included liberals like Garry Kasparov.
Limonov, its leader, is a former Kremlin critic who has supported President Vladimir Putin's intervention in Ukraine.
Pro-Kremlin lawmakers and commentators branded Makarevich a traitor after he gave concerts in Ukraine for refugees from the eastern part of the country, where government forces have been fighting pro-Russian separatists.