Twenty-eight people have been arrested in Mahalla for their alleged role in violent protests in the city on Friday.
They will be detained for 15 days pending investigations, Mohamed El-Tekhy, chief prosecutor of Eastern Tanta, said on Sunday.
Protests dubbed 'The Day of Putting the Regime on Trial' took place in Cairo and other major cities across Egypt on Friday, including Port Said which has seen an almost week-long civil disobedience campaign.
The 28 detainees, who were arrested on Saturday and whose names have not been released, are accused of throwing Molotov cocktails, attacking police stations, forcing shop owners to close early, and blocking railway tracks and main roads.
Mahalla has seen ongoing clashes every Friday since the second anniversary of the January 25 Revolution. Among the protesters' demands has been justice for slain political activist Mohamed El-Gendy, a Tanta native, who died on 4 February after allegedly being tortured to death in police custody.
On Sunday, protesters in Mahalla began a civil disobedience campaign, blocking the railway line in the city.
Mahalla is an industrial city in the Nile Delta governorate of Gharbiya.