Thousands of supporters of ousted president Mohamed Morsi also took to the streets against what they regard as a military coup.

Both camps have already massed in force in Cairo and across Egypt even before the protests planned gathering time.

Protesters in the square cheered as the speaker on the main stage announced that ousted leader Mohamed Morsi would be in detention for 15 days pending investigations into charges he has done.

Many protesters held pictures of army chief and defense minister Abdel Fattah El-Sisi and chanted against the Muslim Brotherhood, telling Ahram Online that they are in the square to defend the country "against terrorism."

El-Sisi called on Wednesday for Egyptian citizens to take to the streets to give the military “a mandate” to deal with “violence and terrorism.”

The Muslim Brotherhood argue that the military-backed ouster of Morsi on 3 July was an illegitimate coup d’état.

Egypt's military leaders gave the Islamist group until Saturday afternoon to sign up to political reconciliation, pledging however to protect peaceful protesters of any affiliation, yet "turn its guns" on those resorting to violence and terrorism.

The main opposition groups have called for pro-army marches to kick-off at 4 and 5 pm. Crowds are expected to gather in large numbers after sunset, when Muslims end the day’s Ramadan fasting.

Clashes broke out between supporters and opponents of ousted president Mohamed Morsi in the central Cairo neighborhood of Shubra on Friday, witnesses told AFP.

The clashes erupted early in the afternoon, the witnesses said. Live footage on satellite station ONTV showed crowds throwing rocks at each other in the neighborhood. Medics said clashes left at least 10 injured.

Large-scale reinforcements have been sent to secure Friday's rallies in Cairo. Dozens of police and military armored vehicles have been stationed outside the Ittihadiya presidential palace in Cairo's Heliopolis district and around Tahrir Square, Ahram Arabic news website reported.

A number of tents had been pitched early Friday morning outside the palace, where pro-military demonstrators are expected to gather.

Demonstrations were also planned by Islamist backers of ousted president Mohamed Morsi. Thousands from across Egypt's provincial towns have massed outside the Rabaa Al-Adawiya Mosque in northern Cairo, Ahram Arabic news website said.

Protesters chanted anti-military, pro-Morsi and Islamist slogans.

NJF/NJF