Egyptian security forces said they have taken measures to secure police stations and buildings in Cairo and Giza.

The security forces also said they will respond with live ammunition – as stipulated by the law – against any attempts to attack police facilities. Special Forces armed with deadly weapons have been deployed at interior ministry facilities, a security source told state news agency MENA.

The forces have been instructed to use live bullets against any attack, the source told MENA. Security patrols were also deployed at main roads and highways to respond to any attacks against private and public property, the source added.

Violence erupted in Egypt on Wednesday after a deadly crackdown by police forces on supporters of deposed president Mohamed Morsi who were holding sit-ins at the Rabaa Al-Adawiya Mosque in Cairo and Al-Nahda Square in Giza.

The sit-ins were dispersed by police, leaving a death toll – still rising – of at least 638 dead and thousands injured, according to official figures.

The Muslim Brotherhood, leading the sit-ins, claims the real number of dead is in the thousands and has called for mass protests on Friday and to show anger against the bloody security crackdown on Islamists, and against what they describe as a coup against legitimacy

Protests are planned to start off from about 30 mosques in Cairo and Giza to march to Cairo's Ramses Square close to downtown.

Police and military armed vehicles have blocked all roads leading to Rabaa Al-Adawiya.

The security forces have also blocked roads leading to Cairo’s Tahrir Square, which is near Ramses Square. The site of the Brotherhood’s planned protest.

Tahrir Square was the epicentre of anti-Morsi protests before his ouster and where Egyptians – including the Muslim Brotherhood – gathered in 2011 to oust long time dictator Hosni Mubarak.

Security forces also blocked roads leading to Moustafa Mahmoud Square in the Mohandeseen district in Giza, where Morsi supporters attempted but failed to start another sit-in on Wednesday following the dispersal of the Rabaa Al-Adawiya sit-in.