Egypt's National Coalition to Support Legitimacy – led by the Muslim Brotherhood – has called for rallies on Monday demanding the reinstatement of ousted president Mohamed Morsi.
The coalition announced nine marches to kick off from mosques in Cairo and Giza following afternoon prayers at around 3.30 pm.
Violence soared in Egypt after police forces dispersed two Brotherhood-led sit-ins on Wednesday. At least 800 people, mainly protesters, were killed during dispersals and intermittent clashes between security and pro-Morsi protesters – some of whom were reportedly armed.
On Sunday, at least 36 pro-Morsi detainees were killed while being transferred to Abu Zaabal prison north of Cairo. The interior ministry says they asphyxiated when police fired teargas to abort an escape attempt.
The Muslim Brotherhood argues that the interior ministry's account of the killings hasn't been verified and charges in a statement that security forces "executed" the prisoners for their rejection of the "military coup."
The transitional Egyptian government declared a state of emergency for a period of one month last week following the violent dispersals. Under the emergency laws, the next move was the arrest of over 1000 pro-Morsi protesters and Islamist figures.
The main rally announced by the Brotherhood for Sunday was cancelled and no large rallies were reported elsewhere.
Western nations have been pressuring Cairo to halt the crackdown against the group and its allies.
Egypt's presidency responds that it is facing Muslim Brotherhood terrorism plots.
French President Francois Hollande urged swift elections in Egypt on Sunday, seeming to back Egypt's army-sponsored transitional roadmap which includes parliamentary and presidential elections after constitutional amendments.
Hollande, however, rejected the violence seen in Egypt during the past week.
"It is unacceptable that there is violence of this level in a great country like Egypt," he said after a meeting with Saudi Foreign Minister Prince Saud al-Faisal.
Saudi Arabia has declared its full support of the military-backed government in Egypt, the kingdom's monarch King Abdullah saying it "stands with its Egyptian brothers against terrorism."
Germany's Chancellor Angela Merkel's office said it would "review" its relations with Egypt, for example.
The European Union has also warned it is reviewing relations with Egypt as bloodshed continues.
The EU is holding an urgent meeting on Monday to discuss the situation, saying that violence must stop immediately.