The station was attacked by 15 people who threw paint-filled shuttlecocks, destroyed ballot boxes and spoiled ballot papers, the Greek Proto Thema newspaper reported.
The center-right New Democracy party has been holding the second and final round of its leadership election on Sunday. The attackers shouted "Teboneras lives," witnesses said. Nikos Teboneras, a mathematics teacher and a teachers' union activist, was killed by a New Democracy member on January 9, 1991, during a student protest at an occupied school.
Early March, members of the Rubicon group seized an office belonging to Greece's ruling Syriza party. The group demanded to close maximum security prisons and free those detained in connection with the case of Conspiracy of the Fire Nuclei radical group who had been on a hunger strike.