The leader of Bulgaria’s nationalist party was arrested yesterday over his role in a fracas with students last month, prosecutors said, the latest in a string of incidents that appear aimed at winning publicity.

In widely broadcast televised footage, Mr Siderov and a group of Attack deputies and supporters entered Bulgaria’s National Academy for Theatre and Film Arts on October 23 and angrily remonstrated with students.

Police had to then escort them from the building and one man appeared to hit Mr Siderov in the face. Yesterday, dozens of angry Attack supporters waved national flags and chanted “mafia” and “fascists” outside the criminal investigation office in Sofia where Siderov and his party colleague Desislav Chukolov were arrested.

Some protesters also waved Russian flags. Mr Siderov and his party want Bulgaria to be aligned again with Russia and have strongly backed Moscow in the Ukraine crisis, including its annexation of Crimea.

Mr Siderov can be held for 72 hours after which a decision can be taken to extend the detention indefinitely.