The Egyptian capital Cairo is poised for renewed protests as supporters of ousted President Mohammed Morsi call for marches after Friday prayers.
It comes two days after authorities broke up Muslim Brotherhood protest camps in the Egyptian capital with the loss of at least 638 lives.
Egypt is in a state of emergency and police have been authorised to use live ammunition in self-defence.
Meanwhile, Egypt’s interim leaders have criticised remarks by President Obama.
On Thursday, Mr Obama condemned the government’s actions in ordering security forces to break up the protest camps, and cancelled joint military exercises.
He said co-operation could not continue while civilians were being killed. However, he stopped short of cutting $1.3bn (£830m) in aid that the US gives to Egypt.
The Egyptian presidency said in a statement on Friday that Mr Obama’s words were “not based on fact” and would “embolden armed groups”.
The Muslim Brotherhood called on its supporters to gather in mosques for Friday prayers and then take to the streets of Cairo.
The group’s leaders say they will hold marches under the slogan “the people want to topple the coup”.
In response, a pro-government group has called on people to protect their neighbourhoods and churches throughout the country.
Egypt’s Coptic Christian community has been targeted by some Islamists who accuse the Church of backing the army’s overthrow of President Morsi last month.
There are fears of renewed bloodshed after authorities said the police were authorised to use live ammunition to protect themselves and key state institutions from attack.
The BBC’s Bethany Bell in Cairo says Egyptians will be watching to see if the Brotherhood will gain some fresh momentum after the crackdown on Wednesday – or if the army will strengthen its grip on power.
