The marches, dubbed as a day of "determination" and calling for the release and reinstatement of deposed president Mohamed Morsi, will kick off from several locations in Egypt's capital.
One march will move from Rabaa Al-Adawya Mosque in Cairo's Nasr City, where Islamists have been staging a sit-in for almost 18 days, to the nearby Republican Guard headquarters in Cairo's Heliopolis district.
Last week, a confrontation between military personnel and pro-Morsi demonstrators outside the Republican Guard building left over 50 protesters killed.
Two marches will leave from Al-Istiqama Mosque in Giza and Al-Asad Ibn El-Furat Mosque in Cairo's Dokki district and will head to Giza's Nahda Square.
Al-Jazeera
... an Arab news network headquartered in Qatar, notorious for carrying al-Qaeda press releases. The name means the Peninsula,as in the Arabian Peninsula. In recent years it has settled in to become slightly less biased than MSNBC, in about the same category as BBC or CBS...
Mubashir Misr reported that another march is on its way to the High Constitutional Court in Cairo's Maadi district.
Earlier on Wednesday, minor scuffles were reported in front of the Cabinet building in downtown Cairo after Morsi supporters marched there to denounce the newly-appointed government officials.