The arrested man, Goran D., will remain in custody for 48 hours and after that he is to be taken to an investigating judge, the electronic media in the Serbian province of Vojvodina said on Friday evening.
The police have been continuing with an investigation in relation to death threats which journalist Dinko Gruhonjic received over his reporting about last year's attack of the neo-Nazi group "Nacionalni stroj" (National Machine) on participants in a panel discussion on anti-fascism.
Gruhonjic, president of Vojvodina's Independent Association of Journalists, received death threats also over his Croat origin.
Insults on ethnic, personal and professional grounds have been levelled against him on the neo-Nazi and racist web site "Stormfront", with the reporter's photo published on the web site.
Serbian President Boris Tadic, leaders of the Vojvodina government, and professional and nongovernmental organisations have urged protection for Gruhonjic, and an investigation to find those responsible for the incident.