Protesters attacked the Tanta police station and the headquarters of the Gharbiya Security Directorate following the funeral Monday of activist Mohamed al-Gendy, al-Masry al-Youm reported.
The demonstrators threw stones and Molotov cocktails at police, who fired teargas to push the crowd back from government buildings.
Police said the clashes continued Monday evening, the Middle East News Agency MENA reported.
Gendy, a member of the Popular Current, disappeared Jan. 28 in Cairo. Four days later he was found in critical condition at a hospital in Ramses where he died.
His family has accused police of torturing him.