ZAGREB, Croatia —  Croatia's prime minister should condemn the three-hour police questioning of a man who started a Facebook group that criticized the premier, an opposition leader said.

Social Democratic Party leader Zoran Milanovic said Monday the incident sets a "dangerous precedent" that endangers freedom of expression and should be criticized by Prime Minister Ivo Sanader.

Niksa Klecak was detained Friday after initiating an anti-Sanader group on the online social networking site Facebook. Police say they questioned him because of a photo montage showing the premier in a Nazi uniform. Nazi symbols are banned under Croatian law.

Police say Klecak was released after proving he had not posted the photo.