Members of the Russian performance-art group Pussy Riot were attacked by Cossacks in Sochi.
Former prison inmates Nadezhda Tolokonnikova said on Twitter that Cossacks attacked the group on February 19 as it performed a song criticizing Russian President Vladimir Putin near the Sochi Olympics banner.
Video showed the Cossacks whipping group members and spraying them with pepper gas.
Maria Alyokhina posted pictures on Twitter of her chest showing bruising.
Tolokonnikova's husband, Pyotr Verzilov, said he was taken to a hospital after getting pepper gas in his eyes.
WATCH: Pussy Riot performers whipped by Cossacks in Sochi.
The activities of Cossacks, a traditional Russian military force, are sometimes approved by the authorities to boost security.
The attack came a day after Tolokonnikova and Alyokhina were detained by police in Sochi for several hours, allegedly in connection with a theft case.
Based on reporting by AFP and AP