Rival protests by supporters and opponents of former president Mohamed Morsi will take place in Cairo on Friday. Both sides have predicted a high turnout.
The military has warned it will clampdown on any violence and urged protesters to eschew vandalism against military facilities.
Pro-Morsi protesters gathered outside Rabaa Al-Adawiya Mosque in Cairo's Nasr City on Friday morning. They handed out leaflets to passersby, waved flags and held aloft posters of the toppled Islamist leader. On the main stage, a big banner written in English said “democracy against coup.”
Ten ambulances arrived near the mosque during the morning, according to Al-Ahram Arabic news website.
Supporters of Mohamed Morsi have been protesting continuously since the army removed him from the presidency on 3 July following mass protests.
A newly formed coalition of Islamist parties – led by Morsi's Muslim Brotherhood – has called on the president's backers to travel from across the country to attend protests in Cairo and Giza dubbed 'Breaking the Coup'. Marches will set out from 18 mosques following noon prayers.
Protests will also take place in a number of governorates.
Pro-Morsi protests have occasionally boiled over into violent confrontations with the former president's opponents and security forces.
Seven people were killed and hundreds injured on Monday night during clashes between the police and pro-Morsi protesters in downtown Cairo and Giza.
Meanwhile, Rebel (Tamarod) – the driving force behind protests on 30 June calling for Morsi's removal – and other revolutionary forces are preparing for rallies on Friday at Cairo's Ittihadiya presidential palace and Tahrir Square, and in other towns across the country.
April 6 Youth Movement (Democratic Front) urged protesters to arrive at protests early on Friday to foil alleged plans by the Brotherhood to occupy the usual anti-Morsi protest sites.
Demonstrators will "press for the goals of the revolution to be fulfilled and condemn terrorism by Morsi supporters," in reference to recent deadly attacks on security forces in the Sinai Peninsula.
The restive peninsula has witnessed an upsurge in attacks by hard-line Islamist militants since Morsi's overthrow, leaving several policemen and soldiers dead.
A policeman was shot dead and another wounded in an attack by suspected militants on Thursday.
Egypt's interim president Adly Mansour vowed on Thursday to "fight the battle for security and preserve the revolution."
The pro-Morsi camp has refused to recognise what they describe as a "coup government," with Brotherhood officials vowing during a meeting with EU foreign policy chief Catharine Ashton that they would press ahead with street protests until the Islamist leader is reinstated.
Morsi has been held incommunicado at an undisclosed location since his ouster on 3 July.
His allies have remained encamped in Cairo and Giza since then. They have also marched and rallied across Cairo and other provincial towns.
Friday's protests coincide with the fortieth anniversary of the 10th of Ramadan war with Israel, according to the Islamic calendar.