ATHENS, Greece — Anarchist groups in Athens have occupied a downtown university building and have urged nearby residents to attack police by dropping flower pots from their balconies, ahead of an annual protest march frequently marred by violence.

Police on Wednesday said more than 5,000 officers would be on duty for the march matching the Nov. 17 anniversary of a deadly 1973 student uprising against a dictatorship that collapsed the following year.

Often attracting tens of thousands of demonstrators, the yearly march ends at the U.S. Embassy.

Anarchist protesters are occupying the Polytechnic building in central Athens, and have distributed flyers in Greek and English in the surrounding neighborhood, urging residents to gather information on police and attack them.