Former political prisoner of the Kremlin, public activist Volodymyr Balukh, who was beaten up in Kyiv and hospitalized on Tuesday night, is in intensive care unit as of 16:30 of Tuesday, Iryna Gerashchenko, co-chairman of the parliamentary faction European Solidarity, said.

"Volodymyr Balukh is in intensive care unit now," Gerashchenko wrote on her Facebook page at 16:27 on Tuesday.

She later updated her post with preliminary details of the incident.

"According to preliminary information, the Kremlin's political prisoners gathered together to congratulate each other on the anniversary of their liberation. There was a Russian-speaking company nearby. Volodia made a remark, it looks like these people could then track him down .... I received this information from [Deputy Chairman of the Mejlis of the Crimean Tatar People, Ukrainian MP] Akhtem Chiygoz," Gerashchenko wrote.

According to her, Balukh is now in serious condition and is placed in the emergency hospital, where the ambulance brought him at noon.

"The operation has just ended, he was transferred to the intensive care unit. Volodia has a severe head injury, the operation was on his head, his condition is serious," the parliamentarian wrote on Facebook.