The police in the Bjelovar-Bilogora County said have said that a Molotov cocktail was thrown at the offices of the local Croatian Democratic Union (HDZ) party branch on the night between Saturday and Sunday.
Local police spokesman Drazen Medved said the Molotov cocktail caused minor damage, burning the doormat at the entrance to the party's offices.
The head of the county HDZ branch, Kreso Jelavic, said the local HDZ did not deserve such an attack.
The HDZ offices in Bjelovar are owned by the town authorities and the party took a lease on them in 1990.