The National Coalition for Supporting Legitimacy said it has organised a march from Rabaa al-Adaweya Mosque in Cairo to the presidential palace on Wednesday after the late evening "Taraweeh" prayers.
The Islamist coalition, which supports former president Mohamed Mursi, groups the Muslim Brotherhood and its Freedom and Justice Party, the hardline group al-Gamaa al-Islamiya and other Islamist parties.
During the march, the supporters will carry symbolic coffins of those who fell victim in last Monday's violent confrontations by the Republican Guard's headquarters.
Army forces have closed Merghany Street, which leads to the palace, on Wednesday in preparation for the demonstration.
The platform at the pro-Mursi sit-in in Rabaa said that around one million broke their fast on the first day of the holy month of Ramadan at the sit-in.
Thousands of the Salafi Front members from Cairo and other governorates took part in the sit-in.
The front issued and distributed a statement condemning what some media outlets broadcast on the intention of some Islamists to blow up their supporters in an attempt to win sympathy.