Vandals attacked the grave in the night between Saturday and Sunday and again in the night between Wednesday and Thursday. Both times they removed the five-pointed red star from the monument and tore down a concrete vase.
A Zagreb police official informed a news conference of the incidents in Zagreb on Friday, adding that the damage was estimated at 500 kuna (approximately 68.5 euros).
The police said that the motive of the vandal acts was not yet known.
The desecration of the common grave of the partisans in Velika Gorica over the weekend was condemned by the local coalition that is in power and that consists of the SDP, HNS, HSLS, HSS and HSP parties.
Associations of Croatian anti-fascists fighters have reported that over 3,000 monuments or memorial plaques, erected in tribute to partisans, have been demolished or damaged since 1990.