Violence is yet again threatening to engulf the Arab world's most populous nation as fierce clashes have broken out in the key Egyptian cities of Cairo and Alexandria.

Scores of supporters and opponents of deposed president Mohamed Morsi have taken to the streets, triggering a massive crackdown by the powerful Egyptian army.

At least 10 pro-Morsi protesters were killed in the early hours, while scores are believed to have died during Friday's protests.

Hundreds of others have been injured, according to local reports. The Muslim Brotherhood claims a higher number of its members have died, but the claim could not be independently verified.

Many were shot dead by the army, according to unconfirmed reports. Media reports say the rattle of gunfire could be heard in some areas. The presence of rooftop snipers has also been reported.

Military helicopters continue to swirl above camps of Morsi's supporters in Cairo.

The latest round of violence has led to speculation that the military could be preparing to deliver a death blow to the Muslim Brotherhood.

Thousands of protesters heeded the army chief's call to flock towards Cairo's iconic Tahrir Square in a show of support for the army's actions. Army chief Abdel Fattah al-Sisi urged Egyptians to give the military the mandate for the removal of Morsi and to fight against "terrorism".

The army-backed interim administration will take the protests "to an end soon and in a legal manner" said interim Interior Minister Mohamed Ibrahim, according to the state-run newspaper Al Ahram.

He said Morsi's supporters are likely to be cleared from the Rabaa al-Adawiya mosque in Cairo following residents' complaints over the encampment.

Meanwhile, Morsi, the first democratically elected Egyptian president, has been in an undisclosed location since his overthrow on 3 July.

The ousted president has been formally charged with a number of offences, including murder, and conspiracy with the Palestinian militant outfit Hamas.

A judicial order allowed security forces to question him for 15 days.

Protesters cheer and dance with flares as they gather for a mass protest to support the army in front of the presidential palace in CairoReuters
Protesters standing on power lines cheer as they gather for a mass protest to support the army in front of the presidential palace in CairoReuters
Protesters cheer with flags as they gather for a mass protest to support the army in front of the presidential palace in CairoReuters
Anti-Mursi protesters chant slogans during a mass protest to support the army in Tahrir square in CairoReuters
A protester with her cheek painted with ''I love CC", referring to army chief Abdel-Fattah El-Sisi, gathers with other demonstrators for a mass protest to support the army in front of the presidential palace in CairoReuters