Ukrainian state prosecutors have announced an investigation into Leonid Volkov, a Russian anti-corruption campaigner and former aide to the late opposition leader Alexei Navalny, following claims that he “justified” the invasion of Ukraine, according to a report by Deutsche Welle on Friday.

“The General Prosecutor’s Office of Ukraine would like to clarify that… at this point, no formal criminal charges have been filed,” DW’s Russian service reported.

Prosecutors stated they received two requests to look into Volkov for his critical remarks about Ukrainian officials and the orchestrated death of a far-right Russian militant fighting alongside Ukrainian forces, with one request coming from a member of the Ukrainian parliament.

The investigation into the exiled anti-Kremlin activist is being carried out by Ukrainian security services, and the criminal case is being supervised by the Kyiv City Prosecutor’s Office.

Volkov has recently faced backlash after private messages surfaced in which he accused Denis Kapustin, the founder and leader of the Russian Volunteer Corps, of possessing neo-Nazi beliefs and being a “gift to Kremlin propaganda.” Additionally, he referred to Ukraine’s former intelligence chief, Kyrylo Budanov, as a “despicable provincial political technologist.”

Lithuanian authorities, where Volkov has resided since 2019, are considering revoking his resident permit, citing potential threats to national security.

In response to the controversy, Volkov expressed regret for his “emotional and harsh” remarks in the leaked messages but maintained his stance on Kapustin’s connections to far-right extremist groups and his clothing brand that utilized Nazi imagery.

“I have a strong aversion to neo-Nazis and believe that supporting or engaging with them is wrong,” Volkov stated in an interview with Lithuanian media. “Using evil to combat evil is not a wise choice.”

Moreover, Volkov dismissed assertions made by some Ukrainian officials that all Russian citizens share the blame for the war, labeling claims of collective responsibility as “propagandistic rhetoric” that align with the Kremlin’s narrative of Western hostility toward Russians based on their nationality.

The independent news source SOTA reported Thursday that Ukrainian prosecutors had begun a preliminary investigation into Volkov for allegedly “justifying… Russian aggression,” a charge that could result in a maximum of eight years in prison and a minimum of five.

In light of the criminal inquiry in Ukraine, Volkov posted on X that “this appears to be a situation where further comments could only exacerbate matters.”

Last year, a Russian military court sentenced Volkov to 18 years in absentia on various charges, which included disseminating “fake news” about the Russian military and “rehabilitating Nazism.”

The activist has consistently condemned the invasion of Ukraine.