Volen Siderov, the leader of nationalist Ataka party, and MP Desislav Chukolov, are to appear before the Sofia investigation office on Tuesday after having been summoned at the request of prosecutors.

Bulgaria's Chief Prosecutor's Office said last week it would demand permanent arrest for Siderov and Chukolov over an incident in the night after the October 25 local elections. Days earlier, the two lawmakers had given up their immunity from prosecution, after having refused to do so for weeks.

Separately, the two have already been indicted over an act of hooliganism in front of a liquor store earlier in October.

They are to appear at the investigative office at 11:00 EET. A 72-hour detention will follow, with a court due to rule whether to leave them under permanent arrest.