Tens of thousands of Islamists rallied on Friday at Raba'a al-Adaweya Mosque in Cairo's Nasr City in preparations for a planned million-man demonstration to renounce violence.
Several Islamist parties including the Muslim Brotherhood's Freedom and Justice Party had called for rallying this Friday to declare their support for President Mohamed Mursi.
The Egyptian state television aired footage showing the demonstrators at the mosque holding pro-Mursi banners.
The demonstrators also chanted slogans against the National Salvation Front and lifted banners denouncing media figures and politicians including Mohamed ElBaradei and Hamdeen Sabahi, al-Ahram newspaper reported.
Islamist youth groups spread in the area to facilitate the flow of traffic, the state news agency reported.
Ambulances were deployed around the mosque in case clashes erupt.