Russian opposition activist Leonid Volkov, who is the former chief of staff of the late Russian opposition leader Alexey Navalny, was attacked Tuesday outside his house in the Lithuanian capital of Vilnius, according to Navalny’s spokesperson Kira Yarmysh.

“Leonid Volkov has just been attacked outside his house. Someone broke a car window and sprayed tear gas in his eyes, after which the attacker started hitting Leonid with a hammer,” Yarmysh said in a social media post.

Ivan Zhdanov, the director of Navalny’s Anti-Corruption Foundation, said that Volkov was attacked “near the house” and “they hit his legs with a hammer and hit his arms.”

Images shared by Zhdanov showed Volkov with a swollen face and a bloodied leg. Shattered glass and blood are seen next to a car in another picture. Volkov has since been taken to hospital, Zhdanov said in a social media post.

Lithuanian authorities are investigating Tuesday’s attack, the country’s Foreign Minister Gabrielius Landsbergis said in a post on X. “Perpetrators will have to answer for their crime,” Landsbergis said, describing the attack as “shocking.”

The attack comes days before Russia’s presidential election, seen as a constitutional box-ticking exercise where President Vladimir Putin is all but certain to win a fifth term.

Volkov, who had served as chairman of Navalny’s Anti-Corruption Foundation until 2023, dismissed the elections in February as a “circus,” saying on social media they were meant to signal Putin’s overwhelming mass support.

“You need to understand what the March ‘elections’ mean for Putin. They are a propaganda effort to spread hopelessness” among the electorate, Volkov said.

Navalny, who was the most prominent anti-Putin voice in Russia, died last month in a Russian prison, sparking condemnation from world leaders and accusations from his aides that he had been murdered. The Kremlin has denied any involvement in his death.