Seven people were killed and hundreds wounded last week in clashes between the Islamist Muslim Brotherhood and their critics besieging Mohamed Mursi's graffiti-daubed presidential palace. Both sides plan mass rallies on Tuesday.

The elite Republican Guard has yet to use force to keep protesters away from the palace, which it ringed with tanks, barbed wire and concrete barricades after last week's violence.

Mursi, bruised by calls for his downfall, has rescinded a November 22 decree giving him wide powers but is going ahead with a referendum on Saturday on a constitution seen by his supporters as a triumph for democracy and by many liberals as a betrayal.