Egypt's interim administration has published a timetable for a transition to a new democratic government, hours after the Muslim Brotherhood called for nationwide protests after the army shot dead scores of people outside the elite Republican Guards' headquarters in Cairo Al Jazeera reported.
The interim administration expressed "deep regret" for those killed in violence in Cairo on Monday, adding that it had formed a judicial committee to investigate the events.
Interim president Adly Mansour on Tuesday morning released details of a timetable for parliamentary elections by 2014, after which a date will be announced for a presidential ballot.
The country will have five months to amend the current draft constitution, suspended following Mohamed Morsi's removal last week, ratify it in a referendum, and then hold parliamentary elections, according to the text of the 33-article decree published online.
The whole process will take no more than 210 days, according to the decree, meaning elections by February at the latest.
A senior Muslim Brotherhood official denounced the decree. "A constitutional decree by a man appointed by putchists... brings the country back to square one," said Essam al-Erian in a Facebook posting.
The Brotherhood has called for nationwide protests to take place a day after a deadly shooting at the site of a sit-in by its supporters in Cairo left at least 51 dead and hundreds injured.
The Islamist group released the names of 42 people killed outside the Republican Guards' building, as the interior ministry and military said two policemen and a soldier were also killed.
The military blamed "terrorists", while witnesses, including Brotherhood supporters at the scene, said security forces fired only warning shots and tear gas, and that "thugs" in civilian clothes carried out the shootings.
The US called on the Egyptian army to exercise "maximum restraint", while also condemning "explicit" Brotherhood calls to violence.
'Monday Massacre'
Mohamed Mohamed Ibrahim El-Beltagy, a Brotherhood MP, described the shootings during dawn prayers after police had stormed the site, as a "massacre".
The Egyptian health ministry said that 435 people were injured in the attack. A doctor told Al Jazeera that "the majority of injured had gunshot wounds to the head".
Gehad Haddad, a spokesman for Muslim Brotherhood, said that security forces fired at protesters who demanded the reinstatement of ousted President Mohamed Morsiduring a sit-in near the Republican Guard headquarters in Cairo.
"We have people hit in the head, we have bullets that exploded as they entered the body, cluttering organs and body parts" said Haddad.
In a news conference held in Cairo on Monday, Hany Abdel Latif, Egypt's interior ministry spokesman, said that "the Egyptian police is the force of the people. They are operating for all the Egyptian people, with all their affiliations."
"The Egyptian security forces are working to safeguard the freedom of the Egyptian people following the January 2011 revolution," said Abdel Latif, adding that the police and security apparatus will not protect any particular regime, not "the former, the existing, or the upcoming".
"The Egyptian police is out of the political equation. It can not be part of any political process in any way, shape or form," said Abdel Latif.
Speaking at the same news conference, military spokesman Ahmed Ali blamed the violence on protesters who attacked the Republican Guard headquarters and defended the actions of the security forces, saying that the acted in self-defence against armed men attacking them from various locations, including rooftops.
The military also released footage of what it described as an assault by Morsi supporters on the Republican Guard building in Cairo.
The Muslim Brotherhood's Haddad dismissed the footage as a "total fabrication" and "frivolous Hollywood storytelling".
Calls for an 'uprising'
The Muslim Brotherhood has asked the "international community to stop the "massacres" in the aftermath of last week's ousting of morsi by the military.
The Freedom and Justice Party, the religious group's political arm, demanded "an uprising by the great people of Egypt against those trying to steal their revolution with tanks".
The party, which had the highest number of seats at the parliament before the coup of last week, urged "the international community and international groups and all the free people of the world to intervene to stop further massacres [...] and prevent a new Syria in the Arab world."
Dozens have died and more than 1,000 people have been injured in street clashes between supporters and opponents of Morsi since Wednesday.
On Monday, Egypt closed down the Cairo headquarters of the Muslim Brotherhood, saying weapons were found inside it.
The latest violence further raised political tensions, even as the country's interim leadership struggled to find a consensus on who should be the prime minister.
The Salafist Nour Party announced it was suspending its participation from talks over new government in protest against Monday's fatal shootings.