Two senior members of Ukraine's far-right Svoboda party were charged Friday with rioting, after being questioned in Kyiv in connection with Monday's clashes outside parliament.
Three National Guard officers died of injuries from a grenade explosion during clashes between police and nationalists protesting a constitutional amendment granting more powers to Ukrainian regions including the rebel-held east. More than 140 people were hospitalized. One officer remains in a coma.
Officials said they had found the man, formerly a fighter in a volunteer battalion in the restive east, who is believed to have thrown the grenade.
Svoboda leader Oleh Tyahnybok was summoned for questioning Friday at Ukraine's Interior Ministry. He is quoted by the Kyiv Post as saying that two Svoboda members, former agrarian policy minister Ihor Shvaika and former MP Yuriy Syrotiuk, were charged.
Most of the violent protesters at Monday's rally were Svoboda members.
Speaking in Vladivostok earlier Friday, Russian President Vladimir Putin condemned the deadly clashes and questioned how long Ukrainians would "put up with" the instability convulsing the country.
Putin said the violence constituted "the next enactment of the political confrontation in Ukraine," where the ouster of a pro-Russian president in 2014 brought a Western-oriented government to power.
Putin said that it was "crucial" to give more powers to the separatist Donetsk and Luhansk regions.