Tens of youths staged a protest in Mahalla's El-Khalaa Square, where Eid prayers had earlier taken place, demanding the release of all political prisoners.
"Freedom to all prisoners and justice for all," read one of the protest banners.
Mahalla is one of Egypt's industrial cities and known for its active labour movement. Its mass strikes, especially in 2007, are believed to have set the stage for the January 25 Revolution.
Activists have long been campaigning for the release of political prisoners, especially those convicted in military trials. With Mohamed Morsi now president, activists have staged in the past several days protests demanding he issues a presidential pardon releasing all political prisoners.
A total of 11,879 Egyptians have been detained by the military since last year's January uprising, according to official figures. Of these, 9,714 have since been released.
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