TEHRAN, Dec. 7 (Xinhua) -- Some "rioters" clashed with police around Tehran University campus on Iran's Students Day, the state-run IRNA news agency reported on Monday.

    "Some rioters, who wanted to take disadvantage of the Students Day ceremony, gathered on the streets around Tehran University campus and clashed with police," the report said.

    A ceremony was held commemorating Iran's Students Day in Tehran University on Monday.

    "Some rioters who were not students tried to enter the university to disrupt the ceremony," but they faced police resistance and were dispersed to the streets around the university, the report added.

    Some opposition students' groups had already called for another gathering on the day to voice their support for the opposition leader Mir-Hossein Mousavi who was defeated in Iran's June presidential election.

    The Students Day is an anniversary of the murdering of three students of the University of Tehran on Dec. 7 of 1953 by Iranian police in U.S.-backed Pahlavi regime era. It is celebrated both by religious and secular student movements.