Police forces arrested 73 Muslim Brotherhood supporters in possession of arms and ammunition while they marched in Alexandria on Saturday.
Petrol bombs, jerry cans filled with petrol, leaflets inciting violence, shotguns, and one automatic firearm were found with the arrested demonstrators.
Security forces dispersed several marches supporting former President Mohamed Mursi in several Alexandria districts.
Clashes that broke out between the marching protesters and police forces left three injured, the state-run MENA reported.
Egypt's Health Ministry reported that seven were killed and 47 were injured in clashes in various governorates on Saturday.
The clashes come as Egyptians commemorate the third anniversary of the January 25 Revolution which ousted former President Hosni Mubarak in 2011.