Egypt’s authorities have arrested more than 1,900 people over the past few days, non-governmental organisations say.
It follows demonstrations against the rule of President Abdul Fattah al-Sisi and alleged corruption within the Egyptian military.
Opponents of the president have called for further mass protests across the country on Friday.
Public gatherings of more than 10 people without government approval have been banned since 2013, when Mr Sisi came to power following the military’s ousting of President Mohammed Morsi.
The protests came after videos posted by businessman Mohamed Ali, a 45 year old former actor and military contractor.
He lives in self-imposed exile in Spain and has accused Mr Sisi of corruption – allegations the president denies.