Clashes between security forces and supporters of ousted Islamist president Mohamed Morsi erupted on Friday during protests that followed midday prayers in parts of the capital, Al-Ahram Arabic news website reported.
Protests reportedly took place in the Giza districts of Al-Haram, Faysal, and Lebanon Square.
While dispersing the protests, security forces clashed with the protestors.
In Alexandria, security forces arrested six pro-Morsi protestors taking part in demonstrations in the city.
A total of 51 Morsi supporters were arrested during the protests, according to a statement by the interior ministry.
Aswat Masriya website reported that a high ranking police officer, Khaled Mohamed, was injured by pellet shots to his face while dispersing a protest in Giza.
Genral Nasser Al-Abd told Al-Ahram Arabic news website that the forces arrested the protestors for violating the protest law, which forbids protests that have not received prior authorisation from the authorities.
Clashes also erupted in cities in Upper Egypt including Beni Suef and Qena, according to Aswat Masriya.
On Fridays, Morsi supporters often hold demonstrations against the detainment of their colleagues and against the removal of Morsi from power last summer. In past weeks, the protests were mostly outside the capital.
The National Alliance to Support Legitimacy, a pro-Morsi coalition, has called on supporters to continue protesting in preparation for what they call the "uprising of 3 July 2014."
The group stated that their aim is to "regain the 25 January Revolution" that has been "stolen by the military" since the ouster of Morsi on 3 July last year.