The National Alliance to Support Legitimacy has announced plans for fresh pro-Morsi marches on Monday evening.
The Muslim Brotherhood-led alliance said its supporters would carry coffins to security directorates across Egypt to protest Saturday's killing of dozens of supporters of ousted president Mohamed Morsi.
It will begin a three-day public wake near the Autostrad Road in Cairo to receive condolences for the victims of Saturday's violence in Cairo's Nasr City district.
Eighty civilians, mostly pro-Morsi demonstrators, were killed and 299 injured when police and supporters of the deposed president clashed at the Memorial of the Unknown Soldier Saturday morning.
The alliance also called for a "million-man demonstration" on Tuesday to protest Morsi's ouster.
Morsi was ousted by the army on 3 July amid nationwide protests against his rule.
The Brotherhood has been staging marches and sit-ins in Cairo and elsewhere calling for Morsi's reinstatement.
Morsi's supporters and opponents have clashed frequently since his overthrow.
The interior ministry said it did not fire at protesters during the Saturday clashes.