Four pro-Morsi protesters were shot dead in clashes with security forces in the Suez Canal city of Ismailia, while the state media reported that a policeman was killed in an armed attack on a Cairo checkpoint.
Violence was also reported from different parts of the deeply polarised country, even as military vehicles were deployed across Cairo and Giza, taking up positions in squares and securing important institutions, the state-run EGYNews reported.
Tens of thousands of pro-Morsi supporters took to the streets after Friday prayers for marches as part of what they dubbed as a "Friday of anger" in defiance of the military-imposed state of emergency.
Armoured vehicles and barbed wires blocked all entrances to Tahrir Square, and 22 armoured vehicles were in Mustafa Mahmoud Square.
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Security forces fired birdshot and tear gas to stop supporters from reaching a government building in the northern Egyptian city of Tanta.
"The struggle to overthrow this illegitimate regime is an obligation," the Muslim Brotherhood said on its website today, while urging people to protest peacefully.
The state-run media said the military increased checkpoints at all entrances to Cairo to prevent arms smuggling to protesters.
Also today, at least 20 police officers were wounded when assailants opened fire on two security cars north of Cairo.
The announcement to hold protests came after at least 638 people were killed when security forces cleared two pro-Morsi protest camps at Rabaa al-Adaweya and al-Nahda, ending sit-ins that began after the army toppled Morsi on July 3.