Egypt is poised for widespread rallies as enraged Muslim Brotherhood supporters have pledged to stage "Friday of Anger" protests in the wake of this week's bloodshed.

Supporters of ousted president Mohamed Morsi and Brotherhood leaders said the protesters' anger has spiralled out of control over the crackdown by the army-backed interim administration.

"Anti-coup rallies will depart from all mosques of Cairo and head towards Ramsis square after Jumaa prayer in 'Friday of Anger'," Brotherhood spokesperson Gehad el-Haddad wrote on his Twitter account.

The Egyptian police have been given power to use live ammunition to disperse the protesters if necessary.

"Despite the pain and sorrow over the loss of our martyrs, the latest coup makers' crime has increased our determination to end them," the Brotherhood said in a statement.

Egypt's health ministry raised the death toll during the violent crackdown, which prompted the interim government to issue a state of emergency, and said 638 people were killed. The Brotherhood puts the actual casualty figure at ten times the official toll.

The National Salvation Front, a liberal coalition which opposed Morsi's presidency, has also called for counter-rallies against the "terrorism actions" carried out by the Brotherhood.

Huge crowds are likely to turn up for the demonstrations, raising fears of further bloodshed.

The situation in Egypt resembles the 2011 Arab Spring during the peak of the revolution that overthrew Hosni Mubarak. The climactic day of the anti-Mubarak protest was also called "Friday of Anger".

UN Counsels Restraint

Meanwhile, the UN Security Council has urged Egyptians to exercise calm in spite of the volatile environment.

"The view of council members is that it is important to end violence in Egypt and that the parties exercise maximum restraint. The members first of all expressed their sympathy to the victims and regretted the loss of lives. There was a common desire on the need to stop violence and to advance national reconciliation," Argentine UN ambassador Maria Cristina Perceval told reporters following the 15-member Council's closed-door meeting.

US President Barack Obama has also criticised the interim government's actions sparking a sharp rebuttal from Egypt's presidential office.

In response to Obama's condemnation of the use of force by Cairo's security forces, the Egyptian presidency expressed its fear "that [Obama's] statements not based on facts will strengthen and groups of armed violence and encourage them in their anti-democratic and stability path."